Let me see if I think I know what you're saying. You're saying that you spilt water, cleaned it up as best you could, but the poly won't take where you spilt the water. Is this it?
IF so, yes, you need to let the water dry out of the wood. I'd let it go for 4 or more days. It's OK for the wood to absorbe some moisture. Actually, unless all 4 'sides' of the wood are sealed, the wood absorbes some moisture, and gives it off, over its lifetime (but at a very slow rate). It's natural for a hardwood floor to 'move' due to changes in moisture conditions. That's why it's recommended that before a hardwood floor is installed in the home, it's to be left out in the home for a number of days to get 'acclimated' to the home's interior condition.
If you wiped it up as quick as you said, then you shouldn't have a swelling problem in the short or long term as long as you let the moisture dry out. Yes, it needs to be dry before you can apply the poly, especially if it's oil-based. I'd avoid walking on the floor as much as possible until you're ready to poly it (over the next few days.) There's no need to put a heater or a fan to speed things up. I'd leave the blinds closed too because over these days, you could bleach the maple since it's unprotected. BTW, is the maple a natural maple or is it stained? If it's stained, then 4 days should be plenty for sure because your stain should have sealed the wood. (To be sure, read the info on the can because it should say something about making sure you DON'T use a sand-sealer or something, and that the stain itself is a sealer too.)