I don't bother taking the cap off. Generally I'll try to let stuff sit for about a week before first trying it, but that's just me. I know from DIY that at least some simpler things (single flavor fruit, some tobaccos, menthol) are pretty much fine right up front, but more complex blends do seem to improve. My caramel capp needs about a week before it's really good, and seems to improve more over a couple weeks.