If I were you, I would revisit this issue with the school. If your son is not challenged he is not in the right class. It’s not too late to move up. (And I wouldn’t pay too much attention to parents who say that kids “never” get moved. What may be true for their kids may not be true for yours.) Talk to the teacher or have your son talk to him/her. The chances increase when the current teacher is in support of moving up. Or in talking to the teacher you may learn that the first two weeks were mostly a review of old material with little new content, and that things will pick up quickly and your son will soon find himself challenged enough, so it’s best to stay where he is. Either way, I would start with the teacher. Good luck!