schools do not admit off the waitlist before may 1st. the function of a waitlist is to have kids on retainer if the school does not meet its yield. it is in your sons best interest to pay a deposit at another school that he would genuinely like to attend before may 1st, as getting off the waitlist is rare at a lot of schools. to know his chances, look up the common data set for those schools, there will be waitlist admission info. if/when you pay a deposit at another school and then get off the waiting list, you can write to the school and let them know formally that you will not be attending, at the penalty of losing your deposit.