Not sure what those "special ways" are at Pet Smart, but if I caught you in a pet store, park, or sidewalk with a dog that was visibly under 4 months of age, I would treat you to a lecture like I give to all my puppy buyers.
I have had dogs die of Parvo, and have heard so many tragic stories over the years, that if being nosey saves just one owner from going through that, unappreciated as my advise is, and when followed, doubtless is discounted by someone that I save a great deal of anguish, and money, I still will continue to give it. There are few nastier ways to die than Parvo. The vaccine does not prevent the disease. Keep the pup at home, don't let him lick your shoes.
I don't take dogs off property until they are 6 months old, or more. I waited until Kitty was 10 mos.