Since every flavor i have (aside from TB) says start with 1%, thats what i did. Figured its better to under flavor than over flavor because its easier to add more flavor than more base.
I understand now. It sounds to me like a generic (read: non-committal) label. Either they are lazy, ignorant of what is really needed, or just too afraid to take a stand. So they default to a "safe" level of 1%.
I would not consider 1% as a starting point for any of the flavors you listed (most somewhere higher; Sweetener lower). Of course, to be fair, the percentage desired will vary a
lot based on how you want to use it. Is it a stand-alone? A primary/base note? A secondary/supporting note? Or, is it intended to be completely hidden in the background, and just enhancing one or more notes?
Im definitely going to have to start over, and with the TB ill do it alone this time. But for future reference, when i do mix flavors that say to start with 1%, do i do each one 1%? Or if i do two flavors make each one .5% so it totals 1%?
The dreaded answer no one likes to hear: "it depends...."
In the broadest of terms, with a million exceptions, this is kina-sorta not really but mostly (do you get that I am hedging BIG time?), this is how I do it if I am working from scratch (meaning no recipe as a starting point). It is not the fastest, it is not the best, it is not the way everyone else does it, but it works for me, and stisfies my obsessive compulsive need to understand what is going on in my mix.
First; I need to have an understanding where my primary/dominant/base flavor works best for me by its self. Don't confuse "best" with "this is great; and I can vape it all day." "Best," in this instance means, at what percentage do I like it most for giving me all the flavor(s) the concentrate can give me without having any over-flavoring issues (chemical, fake, off-putting; or even a diminishing level of flavor). This usually requires that I spend a little time testing the ingredient by itself to find my optimal percentage.
This becomes my starting "max total flavor percentage."
Then whatever concentrate(s) I add to it are deducted from the primary concentrate, and added to the new ingredient.
So, as an example of what I am saying so poorly:
I want to use flavor X as the core of my new recipe. I have never used flavor X before. So, I spend a little time working with flavor X by itself, and I learn that it tastes best (for me) at 8%.
Because flavor X is best at 8%; 8% becomes my
starting flavor threshold.
The start of my recipe:
8% flavor X
I know flavor X would probably taste good with flavor Y lingering in the background. I don't want flavor Y to share center-stage with flavor X; but I want it at about half as noticable as flavor X. I have used flavor Y a lot in the past, and I know it is at its optimal percentage (by itself; for
me) is 4%; but I only want it in the background at half strength, so I settle on 2%. (Note: If I have not used flavor Y; I will benefit greatly by spending a bit of time doing some solo tasting here as well.)
Because 8% is my working threshold, and I want to use 2% flavor Y, I reduce flavor X by 2%. Now my growing recipe looks like this:
6% flavor X
2% flavor Y
But, looking at this, and knowing flavor X is not a very dominating flavor, and flavor Y can be kind of assertive. I think I am going to err on the side of caution, and tweak the base note up just a bit (to start anyway). Now the revised looks like this:
Initial Recipe
6.5% flavor X
1.5% flavor Y
(in the PG/VG base of my choice. Nic optional)
Okay, this looks like it is at least in the ballpark, so now is the time to mix my first testing batch. I start
small. If I am fairly confident, this will require little to no aging, I will start with a 5mL batch. If it is going to need time, and multiple tastings, I might do 10mL.
Mix, shake the living daylights out of it (make sure to leave enough room in the bottle to shake well), and set up my atomizer with fresh wick and a clean coil.
Now for the moment of truth; tasting time. I set my hardware to the lower end of its preferred power range, and set the airflow near the middle. I put 0.25-0.50mL into the atomizer and take my first puffs (don't forget to prime the coil(s)). How does it taste? What is it I am tasting? I jot down my thoughts. I take a couple more puffs. How is it tasting now? A couple more notes.
Now I bump up the wattage a bit. Take a puff or two. What's the difference; better/worse? If it is better; I'll bump a bit more and repeat tasting. I continue this with the power until the flavor begins to suffer. Then I back it back to where it was best.
Now I repeat the process with the airflow; opening/closing the air control until the flavor is as good as it is going to get.
Now my hardware seems to be ideally set for this initial recipe. I again consider what the juice tastes like. What do i like about it? What don't I like? how does it compare to what I thought it would taste like? What is missing? Finally I write down my final thoughts of the first tasting, and include what my hardware setup is like.
Now I stop for the day. I go back to vaping one of my other e-liquids; as well as the rest of my day.
The next day I revisit my new creation. I return my hardware to the settings that were "best," and put another 0.25ml into the atty. Take a few puffs. How is it tasting? Re-read my notes from yesterday. How is the flavor tasting today; compared with yesterday? Write another note or two.
If the flavor has changed a lot; I might park the rest; and see if it continues to change tomorrow. If the flavor is pretty much as i remembered from yesterday (no real change), then I might consider my first adjustments.
For adjustments; I find it is best to do only
one at a time. First; what would I think could make this mix better? Well, in our example: flavor X was kinda weak, and I was tasting too much of flavor Y. I also thought flavor X was missing something. Which is more important to me: the weak base note, or the missing something? Because I am not yet sure what is missing, and I
know X is weaker than I want, I am going to focus on that for my first change.
Revised recipe #1
7% flavor X
1% flavor Y
(in the PG/VG base of my choice. Nic optional)
I do
not try to adjust the remaining volume from the first mix. It is too difficult to do with any real precision; and the monetary investment is just too little. I don't throw out the first batch yet (it can be useful for comparison). I mix a fresh batch of this new iteration; and repeat the tasting process (though the hardware is pretty close if not perfect).
If there was little to no change in the first recipe; and the revised recipe needs further adjustment, I might go ahead and do a second revision on the same day (assuming I have time and interest). So now my revised recipe has the balance I want; but it is still missing something. In my mind I am describing this "something" as brightness.
I have used flavor Z successfully, to add brightness to other recipes, so I decide to try it here. (If I am not sure what to use, I may start a new thread in the DIY E-Liquid section of ECF, and explain, and ask for suggestions along with starting percentages... and go from there.)
Now I have a decision to make. Do i merely add the new ingredient? Or, do I need to reduce both the remaining ingredients, to maintain my 8% total flavor "ceiling?" Again, it depends... I "think" 0.10% of flavor Z should be enough to add the missing brightness, so I decide to just go for it. Here is the newest revision:
Revised recipe #1
7% flavor X
1% flavor Y
0.10% flavor Z
(in the PG/VG base of my choice. Nic optional)
Mix... taste... note. Stop for the day.
Revisit the next day(s). If it is what I wanted... hooray! I have a finished recipe. If not; I continue to revise s l o w l y, until I reach my goal (or give up

). These revisions can occur over months, even years, all just depending on how complex, how motivated, and how much I care about its completion.
I have had success right out of the gate on the first try, and I have had recipes with 12 revisions; it just depends on how picky I am being. (And how lucky I get) Mixers that have a good working knowledge of the individual ingredients they are using;
generally have an easier, faster time of it, than mixers just flinging ingredients together on a wing and a prayer.
That said, and to wrap this up for the moment,
this is not the only way to mix, nor is it necessarily best. It just happens to be "best" for
me. What's "best" is what works the most satisfactorily for
you. I imagine other would be willing to share their methods; and I would encourage you to consider how they might work for you.
Oh, and going back to your TB +VBIC question:
If I was going to go the "wing-and-a-prayer" method; I would probably start with a 10% ratio. By which, I mean: if I was starting with 12% TB, I would use no more than 1.2% of VBIC (1.2 is 10% of 12). Taste, give it a day or three, and taste again. Adjust from there. But, figure out where you need the TB to be,
first!

(Some mixers will even mix up a good working single flavor mix of one concentrate, and a second good working single flavor mix of the second concentrate; and then mix the two together, in varying ratios "on the fly" (just like combining two commercial e-liquids together to make something new). This can give them an "in the ballpark" idea of what the final recipe might look like. I haven't had a lot of success with it; but other have.)