I think the key here is to be flexible.
First attempt should be around 85% as Al says something you know you will get no matter what.
Second is usually around 95%, then go for it on your third.
However, if your warmups go crappy, there's a long wait between lifts, the judges are meaner than junk yard dogs, the bench doesn't feel right, whatever. Then adjust downwards as you go.
If you are feeling super good and everything is going your way, adjust upwards.
Your first lifts should be set, but after that, don't get tunnel vision and stick to a plan that sounded good going in, but doesn't seem feasible on the day itself.
And JB has a good point too. Don't get too greedy early on. I went for a big squat (for me) and it really gave me a beating that negatively affected the rest of my lifts that day.
On the bright side, your first meet everything is a PR. You can't go wrong.