Puppies grow and develop much faster than people do. Everyone is familiar with "one human year is equal to about 7 dog years." That is generally true, but.. the FIRST year of a dog's life is actually equal to about 14 years. Knowing and understanding this will help you raise a wonderfully socialized, and well behaved puppy.
From the time a puppy is born to the time it is chosen as a family pet, it ages about two human years. During this very important time, the puppy is "imprinted" with lessons by it's mother and littermates.
Most breeders believe, and research has shown that puppies thrive when they are held in human hands from day one. A puppy that is raised indoors with it's litter., and slowly but consistently introduced to human sights and smells and other stimulus is much more likely to do well with humans later in life.