It's a balancing act and everyone will have different thresholds.
The time will soon pass, but I would keep him off grass and very dog (fox) busy areas until your vet is sure he's safe. But I would do socialising trips at least twice a day as time is short.
I can't let Twiglet have her paws down where other dogs have been until she's 17 weeks! So pity me
She's a Guide Dog pup and they have lost a few to Parvo, so they are ultra cautious, they have three vaccinations - the last at 16 weeks. But I am lucky, I can take her in shops, cafes, garden centres, anywhere I go, so it's a different story.