I just did my first meet back at the beginning of December so this is still relatively fresh in my mind. First, whatever you do to shake off the nerves do it. Second, make sure you smoke your first squat (everything will go smooth after that). Third, open light on all your lifts (you don't want to bomb out of your first meet). Fourth, everyone that said eat and drink a lot above me,
I'll just reiterate that, eat a lot of easily digestible food (I brought boiled eggs, cheese, a sandwich, protein bars, a candy bar, and fruit) and drink a lot of water (but also consider having some caffeine on hand, but don't use it too early or at all if you don't need it) and I also liked having something else to drink like gatorade, but don't overdo the gatorade as you can go into glycemic shock and shut things down.
Fifth thing, I think I did see some guys lose steam come deadlift time (another important reason to open light!), but this was not the case for me. I think this really depends on your level of conditioning also for me the deadlift is my favorite, so the whole day I was looking forward to kicking ass in that lift.
The meet could be long depending on the number of lifters, I think the one I attended was an all day affair (lifting started at 9 AM and didn't end until around 5:30 pm or so) with around 50 lifters. Good luck! Also, it would be good to have a plan of what you are going to do between now and then.