This probably goes without saying, but it is CRITICAL for all WL'ed candidates to move forward with their alternate Plan A. Put down the deposit, fill out the forms -- whatever you need to do. Do not burn your other bridge while waiting to hear whether you are selected from the WL.
USNA has never taken everyone from the WL. Some years, due to lower than expected yield, up to several dozen may receive appointments. The others still received turndowns. And, some years, not one person is taken off the wait list.
Some people may not receive a final decision until well into June -- USNA tries to notify everyone in May but I have seeen years where the process, for some candidates, has lagged. This might be due to late clearing medical waivers or other reasons.
I don't want to be the sound of doom and gloom, but you are best off to assume you will be headed to another school and then, if an appointment comes through, so much the better.