Puppy classes usually don't require for all vaccs to be done, just that what can be done up to that time is done.

 

How long have you lived in your home? Your yard is far cleaner than streets, obviously, so I'd say that as long as you've had your home for over a year, your yard should be fine. That rule is in place because parvo can live outside and survive freezing temperatures for up to a year.

 

Training classes are safe. They only allow vaccinated dogs (other than puppies of course) and will clean the area well. Definitely do not wait to start training classes.

I would ask your vet about the threat of parvo in your area. In some areas there is basically no risk. It also depends on your neighborhood. If you live on a quiet street with only vaccinated dogs, the street is probably safe. If you live in a busy neighborhood with random people going through and stray dogs around, then it's not going to be safe if the risk of parvo is generally high.

 

If you need an alternative way of wearing her out, you could also play with a toy with her inside the house, e.g. play tug-o-war or through a ball. That is what I do when I cannot walk my dog right now but she gets bored. You can also try food puzzle toys like a Kong or a Bob-a-lot. This might tire her out a bit.