I have staying and sealed the tongue and groove boards with 2 coats of poly. I need to restack them until the contractor comes to install them. How long should they dry before I do this?
Unfortunately we can't really provide a good answer because this is 100% about your situation, so there's no generic advice that'll be sure to fit..... other than to wait the full curing time (weeks and weeks) which I assume will not be acceptable.
Best advice here would be to contact the manufacturer of the poly you used and ask them directly. Provide as much detail as you can in your email — number of coats and how they were applied, and probably most importantly, the temp and humidity where you are — so they can advise based on their knowledge of the product's characteristics.
If you were to stack them with the right material in between (e.g. wax paper or the right kind of plastic) the time needed could be a lot shorter. However I don't think there's any way to know, with absolute assurance, what will work.