I would feed him pup food till 1.25 years old 1 for smaller dogs 1.5 for bigger dogs. The biggest thing is keeping them lean don't feed him to much till they are adult. Being heavy is harder on the growing joints and over walkiing also. Also calcium levels in the food may be to high more that 2% is to much 1.5% would be better for a large dog. He sounds like you keep him lean he has plenty of time to grow.