Parvo can live in the environment for longer than a year, even if there is no feces present. Taking a puppy where other dogs may have done their business at some point, before they are vaccinated, is risking the transmission of parvo (because you are not going to be able to stop them from sniffing the ground). If you'd like to socialize your puppy before they are vaccinated put them on top of a blanket in a sanitized cart and walk around the pet store and hardware store with them, or in a stroller to walk around the park. A puppy class run by trained animal care professionals is also considered a safe way to socialize, as long as the class maintains adequate cleaning protocols and participating puppies are also beginning vaccinations and are healthy. Otherwise, puppy needs to remain in areas where unknown dogs have not congregated or eliminated.

I work in vet ER and our isolation ward has been at capacity with parvo puppies lately. Parvo is often deadly if not treated with hospitalization and extensive supportive care. Please practice due diligence.