I have heard from some places that you should call to show your continued interest as well as check on your waitlist status. When should you do this(besides April 9-11)? Also, how do you call but not seem like you are pestering?
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If you are a WL student, I would have your parent call the school. The timing of that call is up to your family, but be sure to avoid calling on their scheduled revisit days and A10.
People may think that if a student calls it will show the AO a level of maturity and initiative. Perhaps, but I don’t believe that it is appropriate for THIS call. A student can convey continued interest in other ways. Emails to the AO updating them on any new accomplishments, or a handwritten note simply expressing that the school remains your first choice, and if you are fortunate enough to be taken off their WL, you will attend.
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Obviously, my answer isn’t working for @sword140 so for his/her sake, I’d really appreciate if more people would please weigh in. Thank you so much! 
Last year when my kid was waitlisted I called AO and spoke to the person we had interviewed with. He was super nice and helpful. Typically they are really rooting for you to get in!
Then my kid wrote a letter from the heart. When we interviewed this year at the school the AO pulled out the letter and said they were all very impressed by it.
I advised my kid just to write the one letter and then respect their time and not overwhelm them. However I just took on a new client who graduated from Choate and e ended up getting off the waitlist by writing them a letter every day all spring and summer!
@bc12345 wait… So are u suggesting that I send a lot of letters?
@sword140 no that is for you and your family to decide!
One letter is enough. More than one (particularly if there is nothing new in the letter) will get you remembered, but not in a good way.
@skieurope ok, thank you.
A couple of emails at most, plus a handwritten note would be fine. Any more than that will seem like pestering.
Keep your hopes up and your expectations low. I know of one beautiful, heartfelt letter that probably ended up in the trash. I now wish I had never mailed it, but instead kept it as a souvenir of my child’s mind at that age.
Like @twinsmama !! That’s why instead I sent my heartfelt letter via PM to a parent on CC ;)-- glad I sent the brief business-like email to the school ! its "nothing personal " - I can imagine how busy they are!