How long does this Fast-Drying Poly take to cure? Could I cover the "dry" poly with cardboard until it cures?

Hello. Although we recommend to wait 24 hours for light use, it would be best to wait 72 hours for a solid cure. This is the time that we recommend before setting rugs and furniture on a floor, if it is used for that purpose. That way, our product has a chance to fully harden. The drying time of our product is based on 77 degrees Fahrenheit, with relative humidity at or below 50%. Higher humidity and lower temperatures will extend the dry/cure times. it is not advised to lay cardboard directly on our uncured product. Regards, Minwax Customer Support