Usually those doing their first meet get a good adrenaline rush and generally do well IF they have been training honestly. It is the most apparent in the deadlift, somewhat helpful in the bench and a little helpful in the squat. However if you haven't been training properly (good depth and paused bench), don't know the commands, and/or can't control your nerves (or psyc yourself out because most likely there will be a lot of people stronger than you) then the added adrenaline can hurt and by the time you get to deads you will be so depressed/upset from a shitty performance it will not help you.
The more experienced you get the more you can psyc yourself up when you want to and the less boost a meet gives you (it is a tiny bit like sex in that regard, still exciting but not quite the same as the first time you did it). Indeed it can get to a point where it is easier to hit a max in the gym than in a meet, even if form is the same, because at a meet you are at a different gym, using a different bar and equipment, most likely lifting at a different time, on different food, surrounded by different people and that can throw you off. To rectify that issue personally I take the attitude that my maxes don't officially count until I do them in a meet, so I try to save the really big lifts for the meet most of the time, especially on something like deads. I also found it harder to psyc myself up for something I have already done before.
Good luck with your meet, hope it goes well