If I were to generalize, then I would say two weeks is the average steeping time. But there are liquids that are just fine straight from the mailer. I'll have to work on a list.
As for steeping by open air, I DON'T recommend it. Oxygen will decrease the life of your liquid RAPIDLY. Since we mix fresh, it does create a problem for those who wait until their nearly out of liquid before they decide to repurchase our products, which in a lot of cases, need more time to do their thing than your patience will allow.
Open air also invites airborn bacteria in your liquid. You don't want to turn your liquid into a petri dish for bacteria! Remember, your breathing the stuff.
Rule of thumb (until we get a list drawn up) is that dairy, caramel, dark chocolate and maceration-based liquids will generally take 2 weeks to settle into their "end flavor".
Some will taste great out of the bottle and will get better with time.
The better way to speed up the steeping process....add a bit of high-proof alcohol. Preferably in the 150+ proof range.
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