Q. My pup had her 1st parvo shot at 3 mos (estimated). My vet gave her a booster at 4 & told me that was all she needed. Is it safe to take her on walks?
A. Yes. Puppies can be allowed in puppy classes a week after their first vaccine (normally between 6-8wks for the first one). And can go for some walks (no dog parks) avoiding areas where strange dogs frequent.
At 16wks, in addition to walking I would possibly have a session or two with a trainer or find a class geared toward pups of similar age. The critical window for socialization has closed now, so you may need help with helping your pup catch up on all she needs.