Here's a couple of analogies I use to give a feel of what steeping does:
1. Powdered drink mix in a glass of water. Stir. Notice how quickly it dissolves. Within seconds, it is ready to drink. No steeping at all.
2. My aunt Cookie's spaghetti sauce: Crush a clove of garlic, and add it to 1 quart of tomato sauce. Stir. You won't taste much garlic unless you actually taste a chunk directly. Simmer for 20 minutes, to let the garlic flavor mix with the tomato sauce. Cool, and put in refrigerator for tomorrow. More of the garlic flavor will seep out, and mellow. This is 'steeping'. (it's even better after 48 hours)
DIY
eliquid recipes are somewhere between these two, with some ready to
vape right away, and others needing more time to mix. Some try to speed the 'steeping' time by putting the bottle in a cup of hot water. Others just set the bottle aside for a day or two (even a month or two) to let the flavors blend properly. You already know that too much flavor is a bad as too little, so until the flavor blends though thoroughly, you'll just have a mix of too much and too little. Finding the amount of steeping you like for each flavor is a matter of trial-and-error (and suggestions from experienced DIYers, who learned the same way you are).
I have some mixes that I make 10ml at a time, and use right away. Others I use a rotation of two 30 or 50ml bottles, so as I am
vaping one, the other is steeping. As I finish off that first bottle, I make a new 50ml batch to steep while I vape the now-steeped 2nd bottle. There are a few that I don't care for when they're steeped that long, so I make 5ml batches of those, and vape right away. All depends on what you find you like.