I think it's just a balance. You have to weigh risk vs. reward for different scenarios. Going to friends and neighbors homes with no dogs/ vaccinated dogs was pretty safe. Going to Lowes (where we even had him ride in the cart with a blanket down) we felt was very safe. Having lots and lots of people over to meet the pup was safe. Sitting outside a coffee shop on the weekend with the pup on a blanket or your lap we thought was safe. Puppy classes or social hours requiring dogs be current on vaccines - I thought was pretty safe as well.
Going to a dog park - probably not safe. Walking around - at least around my area where there are lots of dogs getting walked/ wild animals - not the best situation. Petstores - didn't go there either. Vet's office - we kept him in his crate until the Doc saw him.
Also, don't forget all the socialization you can do in the home - loud noises, getting used to grooming, kids, etc. If you live in an area where people hang out outside/ walk past, just sit on your porch/driveway with him and people/dog/kid/bicycle/skateboard watch. If the dog has a good temperament to start, I've heard waiting until he's had he shots shouldn't affect him that much, but I understand the desire to start early. We had him out and about when we could and then, once vaccinated, took him everywhere with us (that was allowed of course).