Puppy foods can be introduced at weaning by softening a few kibbles with warm water not with the milk and leave them close to their bed. If they do not accept the food readily you can also put a small spot of soften food on their front paws, which they will tend to lick and hence become familiar to the smell and taste. Once they have accepted the moistened food an additional bowl of dry food can be placed nearby and the quantity of moistened food reduced, which will encourage them to move across to the dry. Once they have all accepted the dry food the moistened food can be removed, but always allow them nearby access to clean, fresh water at all times.