I rescue abused and abandoned cats and kittens. You can begin a high-grade dry kitten food or Kitten Chow as early as 5-6 weeks of age. You need to soak it in water at that age to make a kind of "mush". If the kitten is still with its mother, they will continue to nurse until the mommy cat is done and you can still begin the switch to dry food. You can also mix the dry food with a little bit of canned wet food formulated for kittens. I always have dry food out for my "kids" so they can nibble all day. They are fed canned food once a day. Whatever you do, never give your kitten or adult cat milk. This will cause diarrhea and distress in your pet. Always have a fresh bowl of water next to their food dish. Best of luck.