If you're watching over a litter of newborn puppies whose mother's caring for them, you can simply observe the loving parental care in action, up to a point. If the puppies have been orphaned, however, you'll have to determine on your own when to switch from formula to soft chow.
About Weaning
Weaning is a process that involves puppies making the slow move from feeding exclusively on their mother's milk -- or puppy formula -- to beginning to consume solid commercial foods exclusively. Left alone, the mother begins discouraging her pups from nursing when her teats can't take it anymore, and the pups have to learn to eat other food. In the domestic situation, you're going to lend a hand with puppy food prepared for the pups' ease of consumption. You can't wean a puppy overnight, however, and the whole procedure generally takes a few weeks at a time. Weaning puppies begin by eating a little bit of solid sustenance, albeit in soft, easy-to-manage form of puppy meal blended together with warm water. Puppies will continue to nurse as this is going on, but less and less with time. By the end of weaning, puppies aren't nursing with their mothers or consuming formula at all anymore.
Starting Weaning Puppies
In starting the weaning process, age 5 weeks not only isn't at all early, it's actually on the late side. Puppies can usually start weaning when they're somewhere from 3 to 4 weeks old. The important thing is that the puppies get to stay with their mother until at least 8 weeks.
Finishing Weaning Puppies
Age five weeks is too early to finish weaning. In optimal circumstances, puppies usually complete weaning fully when they're between 7 and 8 weeks old, according to the ASPCA. Do not rush weaning in your puppies, and give the youngsters sufficient time to adapt to eating soft foods before totally stopping with the formula or milk, and to adapt to gradually less soft food until they're eating dry kibble. Weaning usually works well when the puppies have plenty of time to adjust, and it's not a race. Not all puppies take to eating solids as smoothly and seamlessly as others, even within a litter.
Puppy Food Only
Puppies need to start eating puppy food as soon as weaning begins. Select a nutritionally balanced commercial formula that has the dietary needs of puppies in mind. Puppies grow and develop quickly, and their nourishment demands are not the same as those of adult dogs. Adult or "normal" canine food is not yet suitable for them. Puppies need to take in much more energy than mature dogs. Their meals require protein levels of somewhere between 25 percent and 30 percent. Also, bigger dogs take longer to mature, so they'll eat puppy food for longer. Regular visits to your vet are your best means of knowing when an individual pup should move on to adult food.