I would enroll in a very basic puppy class. Also take him for walks in the park or even at the pet store. Keep an eye on him and don't let him be approached until he is ready. If you know anyone with a real stable dog to be around that would be ideal. I believe the first few months are important but I also believe that window of opportunity is always open.
Misty- Samoyed Mix, Tannor- Golden Retriever CGC
Robyn- GSD CGC, TC, Midnite-GSD CGC,TC, Brennan-Golden Retriever CGC, Batman-Husky/Greyhound , Apollo-GSD