I think a big part of these interminable arguments about tabs is based on people using the same words to mean different things. In the following, I'm trying to avoid espousing my personal religion here, I just thought it would be good to try and explain the various sects. Anyway.
Puppies may be placed in new homes once they are eating well on their own. However, they will be better adjusted and make better pets by staying and interacting with littermates and the Mom-dog until they are at least eight weeks old--older generally is better.
For many puppies, eight weeks is the right age. Eight weeks of age has long been accepted as the optimal time to acquire a new pup. By eight weeks, sufficient dog-dog socialization has taken place with mother and litter mates to tide the puppy over until he is old enough to safely meet and play with other dogs in puppy class and dog parks.