You can start your puppy training at home. Teach the pup starting at 8 weeks of age to walk on a leash. Teach sit, down, leave it, wait, etc.
I do not recommend group classes until your pup has had all its vaccinations. The last one should be at 16 weeks or older. And most group classes will also require rabies, which should be done no sooner than 4 weeks after the last vaccination.
If you take your pup to a group class prior to all vaccinations you are taking a huge chance of exposing the pup to deadly diseases. The worst of them being Parvo.
Please ask your vet for their opinion. The trainer conducting the classes will most likely tell you its fine to start after the second vaccination…… because they want enrollment to make money.
The only way you will know if 2 vaccinations are enough is to titer test your pup at the vet. This is a blood draw and sent to the laboratory to see if the pup has an immunity to the diseases for which is being vaccinated for.
Please, for the sake of your pup, wait for all vaccinations to be completed before starting a group obedience class.
This also goes for not taking your pup to Petsmart stores or the like, dog parks, etc…..
And when you go to the vet’s office, do not allow your pup on the ground of the facility; in the waiting room or the exam room until all vaccinations are complete.
Please listen to this advice for the health of your beloved puppy.