ALWAYS save the last inch of DIY eliquid in your bottle and mix the same recipe ON TOP of that one inch in the same bottle.
Makes a HUGE difference in steep time....it'll change color in a few days, not WEEKS
(learned this doing it, not reading)
I do this as well. It was more of "I dont have another empty bottle but I need to get this juice made today" sort of thing. i don't save an inch though, maybe quarter of an inch.

