A puppy's primary socialization periods last from approximately 3 to 13 weeks of age. (fithound.com)
Since the primary socialization period for dogs ends by 3 months of age, puppy socialization classes are most valuable for puppies 8 weeks of age and older. (vanecovillage.com)
The best time to teach them is during the primary socialization period, which is roughly from 2 to 7 weeks of age. (anticruelty.org)