Hi
The first issue is early socialization vs parvovirus. There's several good articles about this but in my opinion the damage caused by lack of socialization is much more probable than the risk of parvovirus. Today I would risk a bit more with my puppy, even outside.
We went on car rides from day 1, almost all days. This is a secure way to absorb a lot of things and get used to car. We also had treats on our rides... everytime appears something new or she explores... we reward. And a relaxed attitude is important, if we react to things like "everything is cool" the puppy will understand there's no reason to fear
We always tried not to repeat the same places so she learn the world can be diverse and unpredictable. Crowded places, nature, zones with dogs on gates, city traffic, commercial centres, beach, football playground... encouraging people to stroke her, etc etc etc.
I would put on top the contact with many different people (stroking) and dogs (off the leash).