I do Nic, PG, VG, then flavorings. It's all shaken up once you finish. I don't think that order makes a lot of difference. VG is thicker than PG, so having VG on top of PG probably allows gravity to infiltrate the thicker ingredient into the thinner ingredient somewhat, but it's shaking, stirring, or mixing with something like a magnetic mixer that completes the process.
I don't have a mixer, so I shake all my bottles for about 30 seconds each a two or
three times a day and try them periodically to determine how well steeping is improving the mix. I'm finding that my Hangsen flavors steep faster than my Flavorart flavors, but all get better with time.
My Flavourart Desert Ship took two weeks to get to a stable level that I wanted to
vape. Now, it's good. It was nasty on day 2. Flavourart DS is good now after two weeks. The FA 7 Leaves was good the next day and better later on. Go figure.
Hangsen Desert Ship,
tobacco, and Highway were vapable on day 2 with no off taste, but a little weak on flavor. They steeped into really good flavor after a week. I started off with the Hangsens at 7% flavor and took them up to 10% after the first week. A few more days and they should be where I want them.