It’s going to take more than 24 hours to dry out the stairs completely after using a polyurethane coating on it. You should never start walking on the stares before 24 hours, as it can ruin the whole thing. Also, you need to wait for an extended period before you move on to bringing the furniture in place through the stairs. You must wait for at least 106 hours before you choose to do that. That’s going to give the stairs enough time to soak the whole thing, dry out, and cure.