Perhaps my own personal bias here, but for me a puppy of 3 months old is too young to benefit greatly from a group class. At that age I prefer to work one-on-one with the puppy with little or no distraction. Use treats to lure the puppy to perform basic stuff, sit, down, come...etc.
Keep it short and fun, "structured playtime" is how I like to think of it... The main goal at that age, from my perspective anyway, is to bond with the puppy through play, encourage him to follow you, firm up potty training, etc., more formal training can come later...
It's not the size of the dog in the fight, it's the size of the fight in the dog. Mark Twain