I measure out my nic base, add in flavorings and then shake, add in my VG and shake then add in pg, if needed based on the mix I'm going for and shake for about a min.... If I remember, I'll take the top off and let it breathe for a bit and then shake again after an hour, then I'll let it sit for a few hours up to a day without the top.
I only started DIY a little over a week ago, so I'm still working things into a schedule.... I'll randomly shake the bottles for a few seconds throughout the day, I'll randomly squeeze the bottles to exchange the air....