When shampooing with a cleaner, most processes take four to six hours from start to finish. The range may be higher or lower depending on your particular machine, shampoo, and carpet. It’s best to plan ahead, as you may want to evacuate the house for the drying process — especially if there is a chemical odor associated with your shampoo.;It may also be worth running over the carpet a second time with cold water in the machine to remove any leftover shampoo without further activating it.