"The Primary and most important time for puppy socialization is the first 3
months of life." (American Veterinary Society of Animal Behavior, https://avsab.org/resources/position-statements/)
The AVSAB Position Statement on Puppy Socialization has not changed since it's writing, and we think for good reason. Unfortunately we've been hearing that some breeders and certain shelters in the area are advocating that new pup owners should avoid socialization classes until their dog is at least fully vaccinated, which occurs around age 16+ weeks (4mos of age). "In general, puppies can start puppy socialization classes as early as 7-8 weeks of age. Puppies should receive a minimum of one set of vaccines at least 7 days prior to the first class and a first deworming. They should be kept up-to-date on vaccines throughout the class.
Further, "Dogs that are appropriately socialized as puppies are less likely to exhibit behavioral problems as adults, including aggression and fearfulness." (Puppy parties and beyond: the role of early age socialization practices on adult dog behavior, Tiffani J Howell, Tammie King, and Pauleen C Bennett, Published online 2015 Apr 29. doi: 10.2147/VMRR.S6208).
