Elder John Michael Gilbert
2005 N 900 E Unit 146
Provo UT 84602
DearElder.com is a great website that you can write an email to John, and they will print and deliver it to him daily at no cost! This is a great way to help keep him going during those first two difficult weeks! Sign up on their website and John's address above has all the initial details you will need to get started.
If you would like to send a small package while he is there (treats, pens, whatever) check the shipping dates to make sure it will arrive while he is still there. Packages received after the Elder has left for his mission field will be returned to sender, not forwarded on.