"8 to 12 weeks,or after the're weaned."Changing different types of dry dog food too quickly can upset a puppy's stomach.For example,the first week is "Iams",and the second week is "Max".That can upset a puppies stomach. Be patient and give it time.If your dog refuses to eat the dry food,put bits of cooked chicken or cooked steak at the bottom of the dish.That way he has a reason to eat the dog food,to get his/her prize.I do that with my German Shepherd Max,he's 6.
8-12 weeks after
i think it could begin right now, but you should ask your breeder, because if i am wrong, it may hurt your dog.