Our boy came to us at 4 months, and never barked.
Our very first obedience class he barked at another dog (as they all did!
) We were told to tell him "Quite" and then when he was say "Good Quiet!" and give him a treat.
The only thing he took out of that first week was bark, be told quiet, be quiet, get treat! And he tried to practice it at home. Took quite a few weeks to break him of that bad habit. So treats can be msused, and he can train you with them!
As for treats in general, we still use them but more carefully,being sure to always be reinforcing positive and not negative behaviors.
And it is NEVER to late for classes. And look around, we found our local training club had classes for half the price of other trainers.
Doc is the first dog I have had that we have done any formal classes with. We are in our third class (6 week session) now amnd it is worth every penny and every hour we've spent. We may not have a perfect dog but he is already better behaved then most of the other dogs I know, and getting better by the week.
Enjoy him, and your time together!