We start all of our puppies at three weeks of age on going to the potty on an artificial grass pad system or pee pad with grate systems. Puppies generally adapt very well to going outside, or they can continue to use one of the systems they are already familiar with if it is more convenient for you. Those who live in an apartment without an easily-accessible yard or those who add on of our very small dogs to their family sometimes find that it is easiest for them to use an indoor system or to go back and forth between indoor and outdoor potty locations.