Even if juice is "custom" mixed to a specific nic level and PG/VG, sometimes a "base, flavorless, nic free" steeping happens, and all that's added is the right proportion of PG steeped base, PG steeped VG, and nicotine, then all mixed together. I don't think all mixes are assembled completely from scratch. With that said, it's also possible with some custom juice makers who will let you select all of your flavors, and include things like distilled water or other unusual "requests" well those juices may require steeping. It's also possible to get a steeped, and a less steeped bottle, depending on when/how flavor-makers prepare their batches. If you don't find a problem with the juice, it's fine to just vape it. Otherwise, if it seems weak, or unready, you may have to wait a period of time.
I never steep with the bottle open, although I will sometimes "air" my mixes for 5--10 minutes periodically (and I mean, not often) because I use Distilled water in my mixes and don't want it all evaporating. There is really no "one" practice, most DIY folks figure out a process that works for them, and then uses it, with the caveat that some flavors (think custards, cremes tobaccos) may require more steeping time than say fruit flavors and some other mixes.
This is why keeping notes at every stage, even when it feels laborious in the beginning, tends to generate increasingly excellent, repeatable results.
Best of luck,
Anna
I never steep with the bottle open, although I will sometimes "air" my mixes for 5--10 minutes periodically (and I mean, not often) because I use Distilled water in my mixes and don't want it all evaporating. There is really no "one" practice, most DIY folks figure out a process that works for them, and then uses it, with the caveat that some flavors (think custards, cremes tobaccos) may require more steeping time than say fruit flavors and some other mixes.
This is why keeping notes at every stage, even when it feels laborious in the beginning, tends to generate increasingly excellent, repeatable results.
Best of luck,
Anna