I assume from your question that your puppy is currently eating a combination of chicken, baby food and yogurt. If he is eating that well multiple times per day without you having to entice him and if his attitude and bowel movements are good you can begin to reduce the special foods which will push him toward needing to consume the puppy food. It is a good idea to try a couple different brands of puppy food and also to try mixing the special food with canned puppy food and make the change gradually. If you are trying to get him on to dry puppy food it is often easier to make the change to canned puppy food first then go from canned to dry gradually.
If you are still having to entice him to eat I would not try to make the change quite yet.