It never hurts to get your name on the list. Worth a call or email to the school to find out what the waiting lists look like, if any.

Here is a fantastic site that ranks schools and has public forums where someone like yourself can talk (ask questions) to other parents who have kids in the school, etc:
http://www.greatschools.net/cgi-bin/ma/private/2323

Here is a link directly to the school if you want to contact them:
http://www.atrium.org/


Here is a link to every property for sale in Watertown. You can click this whenever you are in the browsing mood. It will automatically update every couple minutes with new properties or when things go off the market: http://www.sanfordmullen.com/search-homes-for-sale?LinkID=21808

Good luck with everything! Let us know if we can answer any other questions.