I can see where you're coming from DA, but also why C&B has concerns. I wouldn't try to push Bella into socialisation, if you meet other dogs then deal with it at the time. Also remember that if YOU are expecting her to go off at other dogs then SHE will pick up on your anxiety and body language. While you wait for the next classes to start just enjoy taking them for walks, they don't HAVE to socialise with every dog they meet along the way. I think the classes will be the best way for Bella to socialise as she will be supervised by a trainer.
Way back in the dark ages when I only had 1 or 2 dogs, I have to admit I never made any effort to socialise them - if we met a dog out on our walk I'd see how they reacted, if it was good then they got to say hello and have a play, if it wasn't good then we'd move away. I don't know if it's because I didn't stress over things, but we rarely had problems. At least I don't remember any...lol