Seven weeks is the youngest age that a Labrador puppy should be taken from its littermates, and eight weeks old is often preferable. There is no critical or even best age at which to take a Labrador pup to its new home. It is easier to evaluate an older puppy, and there are no drawbacks to getting an older pup provided it has been raised in an environment of loving care and has not developed bad habits. Do not expect to visit a litter before 6 or 7 weeks of age. Younger puppies are vulnerable to infections and they are not matured enough to be properly evaluated.However, if possible, visit the breeder to meet the pups' mother and other relatives. Your best guide to the quality of the litter is the ethics and expertise of the breeder, so ask plenty of questions.
Five weeks - too young!
Documents that you should expect to see for both parents are 1) evidence that they are AKC registered, 2) hip and elbow evaluationsby the Orthopedic Foundation for Animals (OFA), 3) eye evaluations by a board certified veterinary ophthalmologist (preferably CERF certificate or an OFA Eye Certificate). You should also ask to see a pedigree that contains the same information for as many of the ancestors (grandparents, great-grandparents, etc) as possible. Four or five generations is common in 2012.
Six weeks - too young!
Eight weeks - just right!
Pups should have been wormed, have had dewclaws removed, and had one combination vaccine (against distemper, hepatitis, adenovirus, parainfluenza and parvovirus) at 6 weeks; additional ones at 2-3 week intervals if the pups are older.