Codie, you are one in a million. ;D I can't believe you're planning months ahead when to tell a girl you love her!
I think you should do what Margy suggests - take it slow, give her little hints, and see what she does.
Prom night. Ugh. Boy am I glad I'm not that age anymore.
How does she feel about you, are the feelings returned , if you do tell her and she doesnt have some feelings similar to yours it could put the friendship at risk,.it is however your life and if you feel you have to, then go slowly and see how she responds to affectionate overtures, that could be an indication ..good luck, happy Valentines day ...