A personal best in the gym is just that. It may not be repeated at a competition. Don't let this important learning experience go unrecorded. Enjoy yourself and try to relax. Being anxious or wound up will just drain you.
Contests are long and drawn out.
Be prepared to be there for as long as eight hours. Bring lots of food and water. Take the time after a contest to get together and talk to your fellow lifters. Have some good food, drink and conversation. You deserve it.