American Veterinary Society of Animal Behavior Position Statements on:
The first few weeks with your new puppy are an important time investment in the rest of your lives together! Think of how differences in childhood experiences can affect who humans become for life! The socialization window in puppies ends at 12-16 weeks. Up until this time, we have the opportunity to give pups good experiences with new things, places, people, other animals, and sounds to help turn them into optimists for life. Pups who miss out on a lot of experiences before this time window closes tend to be more worried about both specific things they didn't encounter before and new people, other dogs, and experiences in general. While your puppy's vaccination series will not be complete before 16 weeks, it is important to still socialize him, while considering his disease risk in different situations. For instance, you don't want to take a puppy who is not fully vaccinated to a dog park, or have them around unvaccinated or sick dogs! Start off on the right paw by checking out the resources below and signing up for Puppy Social and Puppy Good Manners class!
(Hint: They recommend socialization before puppy's vaccine series is complete! Read on for details!)
Dog-Human Interactions and Dog Body Language