My main vape is best after 2-3 weeks of steeping time, I vape about 6ml of it a day .. I mix one 120ml bottle of it every 3 weeks and that way I always have a supply that has already steeped. Plus I also have a few 30ml bottles of tobacco juices that I also vape a little of everyday, those require a 3-4 week too, so I always have 2 bottles of each of those .. one that has already steeped and is ready to vape and the other is newly made and has been set aside to steep.
Basically I just make sure to stay ahead of the steeping time by having some that is pre-steeped and ready to vape .. and others that are newly made and are in the steeping process. I do all my mixing in one session, once every 3 weeks, I mark the date on each new bottle, set them into the back of dark closet for a few weeks and shake them every few days.