What do you think socialization is? That is a serious question. People have different ideas of it.
As gsdsar says, it depends on the dog. I got my puppy right before it got so cold and miserable so he missed the ideal socialization time. However, he has very good nerve so anything he is suspicious of he checks out and recovers quickly.
With your puppy, I would say get a trainer and work on behavior modification. Learn the tools. LAT, BAT.
Socialization is not having your puppy meet a ton of people and dogs. It's exposing him to many new things and helping him work through his fear.
Seger vom Sitz von der Hose
Forever loved and missed.....Banshee
~The strength of one's opinion should not exceed their knowledge on the matter~