That is up to you and your vet. You have to weigh the risks and decide at what point you want to move forward. Are you more worried about your puppy getting sick or becoming aggressive or fearful to people or other animals? In this area we have very low incidents of Parvo and Distemper and we have very good puppy classes that disinfect/sanitize before and after each class, so I was able to do puppy class early.
Here are a few links that might help you to decide:
Ch 1: Before You Get Your Puppy | Dog Star Daily
(also just a great website in general for all things puppy!)