I would let her know the basic facts up front - he is reading XYZ books without assistance, he can do these types of math problems that sort of thing. I wouldn't throw out much more up front. The first month of K seems to be filled with FUNTIME, as opposed to much learning. I would have a conference scheduled around 4 weeks into school to really discuss everything. (this is what I did with my son and it worked out well. The teacher was always very willing to chat with me and accept things like extra work, different books and math sheets, etc.)
If only DS's 2nd grade class was so flexible!
