In my opinion no .. your pup won't be vaccinated, and even though there won't be other dogs there at the time that doesn't mean that the outside ground is a safe place for your pup to be! For example parvo can live in soil for several months.
It is important to socialise your young puppy, but this should be whilst being carried (in arms, baby sling etc) and definitely not on the ground outside your garden until she/he is fully vaccinated.