okay lemme teach you about this weird but awesome steeping method. this applies to DIYers as well as people who have many bottles of the same ejuice.
in the wine industry, aging (steeping) wine takes a long long time. but demand is huge. so to keep up with demand, they have to age quicker, which is impossible unless you are martin mcfly. so they devised this steeping method that makes wine (and now beer too) steep less time but have complex taste and flavour - solera steeping.
the idea is simple. take one batch of wine and age it naturally. after a while, mix it with a freshly-produced wine of the same kind and age it naturally as well. so now you have a wine that has this aged taste, and fresh taste (2 flavours). if you do it again, you will have FOUR flavours (aged, semi-aged, aged + semi-aged, fresh) if you keep repeating, the flavours increase exponentially as per geometric sequence. if you mix 10 times, you will have super complex wine that superior tastebuds will be able to taste 512 types of flavour - 1, 2, 4, 8, 16, 32, 64, 128, 256, 512.
now do it with your ejuice. say you have apple cheesecake ejuice for example. buy 1 bottle and steep it like a month or two. then buy a freshly-made bottle and mix it together (goncang pon cukup). now you probably taste a fresh cheesecake, a well cooked cheesecake flavours. steep for a month. then repeat once more.
now you have a very very complex 30ml x 3 ejuice that have multiple levels of taste. bear in mind that this only works for bakery/milky ejuice as it takes longer steeping time to let the flavours come out compared to fruit-based.
also, if your freshly-bought ejuice taste not as good as your steeped old same ejuice, drop a bit of the steeped old same ejuice into the new bottle. shake, and let it sit. the steeped ejuice will help to fasten steeping time of the new bottle ejuice.