There are lots of pros and cons either way. The puppies NEED to be socialized before 12 weeks, and certainly before 16 weeks because by 4 months there can be problems after that with puppies being so suspicious of everything and everyone they didn't see in that important time period.
I am sorry but I disagree with this way of thinking. Puppies HAVE to have exposure to daily things in life, new people ,new sounds, new sights.. I take my puppies out starting after first shots, not to dog parks, not to parks with dogs, but to areas where they can see people,maybe get a few goodies from strangers that I have in my pocket. Maybe see dogs , but not sniff them. Even walking on the street exposes them to cars, kids, etc. Noises, lawnmowers, things in the sky. Short walks, but interesting walks.
Yes, I worked for vets for 35 years, yes ,I know the speil and the dangers, but I have never had a puppy come down with parvo from early socialization but have had puppies that love people, are not afraid of things, sounds etc. I don't give a flying fig if my dog ever goes to a dog park and don't feel my dog needs to be "playmates" to other dogs. As long as they can accept normal everyday things, can realize that people in hats, coats, sunglasses, kids on bikes, on skateboards and all noises are normal, that is what I want.
I know there will probably be lots of negative on this post, but remember one thing. You can keep that puppy home till its had 3 sets of shots and is 16 weeks old to protect it against parvo (or whatever) but if you,during this most important socializing time, go ANYWHERE, to petsmart, Petco, petsop, grocery store, Walmart
and someone walks in the store with parvo germs on their shoes, you can walk through it, into your house and BAM, your puppy is exposed to Parvo. I would rather have a well socialized puppy than one afraid of its own shadow.