Most important....good for you on decreasing your nic levels. I'm trying, but it's a stuggle; especially with the new PV's I just got. I don't have really low nic ejuice and I don't want to lay them down.
The real issue of the thread is steeping, not long term storage. Some people say leaving it in a dark room for 2 weeks makes it taste much better. I doubt that is the case, but if anyone has evidence I'm open to a change of opinion.
I've been vaping for roughly 8 months now. Recently (past 2 months) I've gotten into DIY. I personally purchase 6, 10 and 15ml bottles in black, non-translucent bottles. I first fill the 15ml with whatever flavor I enjoy then let it sit at least a week (Mainly because I have 4 or 5 other flavored 15ml bottles I tend to hit before I get back to the original flavor). Each 15ml is used to fill the 10 or 6ml bottle, depending (I know a ton of people that vape locally and end up letting them try my creations) who I'm around. By the time I get to the original flavor again it tastes crap tons better than it did when I was mixing and just dripping while filling the bottle.
Honestly, the only way you're going to find out for yourself if it works it seems is to just try it. What have you got to lose? Hell, send me $5 and I'll send you a black bottle of one of mine, you try it on day one then let the bottle sit, capped for a week or two and try again. You'll see... There's a partial reason I unknowingly rotate my 15ml bottles I guess.
Just my .02 and experience worth.
EDIT: Think of it this way... You take a pork chop from the store, go home and cook it. Ok, mediocre hearty meal with potatoes and what not... Now, instead of eating that pork chop, you marinade it in the fridge for 48 hours in a brine marinade... Maybe some Lemon and Pepper, whatever... You struggle and eat Toast for those 2 days... until you finally cook that pork chop and say to yourself "Holy ..... that marinade was just what that chop needed!"... Same concept with liquid, it allows everything to blend.