GVDobler posted:I would put the plywood in the basement and let it sit for 3-4 days to settle/swell/dry-out or whatever before nailing it down.
You frame has already done that.
Depending on where you get your wood, it's probably more likely to shrink than expand. Much of the wood you get at the big boxes has moisture in it, and shrinks as it dries. (Found this out the hard way years ago building a deck.) It's good advice to bring wood inside and let it acclimate for awhile before starting to build.
