Potty training should start with the breeder. This type of raising a puppy is called litterbox training and is a regular practice for 15 years at Schnauzers Of Taylor. 
 Puppies raised using this method are easier to housebreak and have fewer accidents in the house, as you are instilling the concept of housebreaking to them at a very young age. They learn from the start there is a place to sleep, a place to play, a place to eat and a place to eliminate and they will carry this concept with them after they leave the breeder. Puppies who are raised in cages where they do not have areas that are separated do not understand this concept. They learn they can eliminate anywhere they wish at any time they wish. Then, after you take them home, you suddenly expect them to understand they cannot pee and poo in the house.

We believe that at 3 to 3 1/2 weeks of age the litter pan or box should be introduced. Puppies learn at a very young age they have a place to potty. 
We use biodegradable and safe pine pellets. 
This in return not only helps the breeder keep the whelping area clean, it makes the puppy easier to housebreak once they go to their new homes. A win-win for everyone. 

Once your puppy arrives home i do not recommend using pee pads. I recommend continuing using a litter pan or a large cat pan in your puppy area. Pups can also learn to go potty outside in your backyard only. No public places. 

Tractor Supply Pellets