What is your nicotine base's ratio, that can matter as well... And, they're not flavor crystals, right, that dissolve into a base? If not, I agree with starting at a low flavoring ratio, and you'll need to let it steep as well, unless it's a shake and vape flavor? If you need
juice now, I might try mixing two different batches, and let the other one steep while you vape the first one, and can compare the results.
I know it sounds crazy, but it actually is (IMO) easier to get really good results just starting with a higher nicotine base (most folks can mix at 100 mg/ml by adding in flavoring, VG and PG, and wind up with more precise results. The mixing calculator does the work (tons of free ones that are just fine on googleplay I like using my phone, as it's small) you just input the required values of what you want to end up with and the calculator will get you precisely to where you want.
I hope that your first batch turns out well though and encourages you to continue down the DIY path, it is so much cheaper and a lot of fun (well, I usually say so but I just organized all my flavorings and mixed 20 bottles of
juice, so I'm a bit drained, heh).
Best of luck, the pinned threads in the DIY forum are really helpful, you may want to take a look....
Anna