No, there is not a specific time to stop, but you should begin immediately as soon as the child gets in the car. Even newborns need to be watched constantly to make sure they are healthy, have not grabbed something they should not, and are comfortable and safe. Only with mirrors like these will the driver of the vehicle be able to view correctly the child in the rear-facing car seat. Even when the child is grown enough to sit facing the front of the vehicle, never stop looking to make sure they are safe and sound.