You will definitely get a variety of responses. One trainer I spoke with believes in starting them at 8 weeks with private lessons. I thought that was a bit young, although Morgan will be 13 weeks tomorrow and just from us working together at home, he can walk on a leash, sit, shake (my favorite), down, stay (most of the time) and come. Like a young child, they seem to learn quickly. I would definitely wait until your baby is fully immunized before any lessons, class or private. We see our vet tomorrow and this is one of the things up for discussion.