You can vape 100% right out of the mail. The more complex flavors and the tobaccos need steeping depending on the % of vg v pg, and also depending on the vendor. I usually let tobaccos steep 2-3 weeks, complex juices that don't have tobacco for about 7-10 days. I usually drip them all after leaving the cap off for 24-48 hours, just to see what they are like. Then after the steeping time I think they need, drip again. Some juices seem to get better with even more than two weeks, Boba's Bounty and HHV Heavenly Tobacco are two such juices IMO.