Just be honest with your parents. Prom is a special occasion and hopefully .. If you show them you can be trusted .. They'll let you go with a date. I would use this year to show them you're responsible and honest and want to earn their trust.
I'm not allowed to date, but I have prom (it comes up in a year, I just wanna prepare way ahead of time) and I wanna take a date. How am I suppose to ask my parents to allow me to do so?
A year is a long way off. You might put off worrying about this until you're closer to the event. In the meantime, find out when, in your family, you're allowed to date. Find out if the rules are different for prom. If your parents are being hard-core about the dating rules, you might just sit down and talk with them about this. But seriously, you've got a lot of time ahead of you. Put this thing on the back burner for a while.
