Congrats!
I practice the "don't ask, don't say" approach. If no one asks, don't mention anything! Like the others said, most kids accept the child readily. Most of the time, it would be only room mom who knows abt it and some kids telling their parents (in just a matter of fact way). If someone brings it up, just smile and say "it's the school's decision" and change subject. Works everytime because most pple would not probe further.