It depends on the type of varnish chosen. Allow at least 24 hours before entering the room if you have chosen a water-based varnish. If you’ve chosen an oil-based analogue, you’ll have to wait at least 48 hours before working on a newly renovated floor.
It is strongly recommended that you wait, for both varieties of varnish, at least three days before relocating the furniture; this is because the top layer of the floor should be absolutely dry. If after 72 hours, you’re not sure if the floor is still dry, wait a little longer to avoid problems.
Although the surface appears dry, it will not be completely hardened before the two-week mark. Thereafter, you can replace the carpets and start regular cleaning or maintenance.