Usually the parvo vaccination is given in a combo-type vaccine with distemper, adenovirus (canine hepatitis), and parainfluenza. Sometimes other vaccines are included in the combo. So, your
puppy may have been given other vaccinations already, in addition to parvo. You need to find out. When you were at the vet's office, you should have been given a vaccination schedule for your puppy, with instructions on when to come back. I would find it very curious if you were not given that.