Any furniture that has been removed from the room for the cleaning is best left off for 24hours.
Any furniture that has exposed timber or metal touching the carpet while it is still damp may react with the moisture and cause a stain, and the stain may be impossible to remove (timber stains especially). We place foam blocks where necessary, under furniture that may cause stains. If you HAVE to return furntiture to carpeted areas sooner than recommended use plastic shopping bags or aluminium foil to act as a barrier.
Do NOT place flat bottomed furniture or plastic roller chair mats back until completely dry as this can suffocate carpet causing mould and rotting.