probably i'm too late to give comments now. totally agree with the rest. The fifth choice is really wasted.
i hope he can enter into your first choice. but let's put aside how likely your son can get into those schools u like. i think it's an appropriate time to prepare well ahead. you may want to list out what other schools you can send letters to and start drafting the letter. or else it'll too late to prepare anything when the result releases.