That class does sound lovely! It's very nice that they took the time to write an extensive, personal note rather than simply spout off the times and details.
I would wait a week, too. Not only will the pup just have its vacs, it will need time to get used to you! A week of feeding it and loving on it will help you establish a trusting relationship, so that when you go into a room with a bunch of strange dogs and people the pup knows that you're a friend.
When my Cedar was a pup, she was picky about treats. We eventually found that Cherrios worked. She was so small, though, that I would break them into quarters, and she just got a little tidbit during training. (You want a treat that the dog can just taste but doesnt have to chew a lot. The chewing takes time and removes the dog's attention from you!)
I'll be interested to hear how your class goes!
Cedar (tri), Willow (blen), Holly (ruby), & Bella (blen)