Relax. Competition jitters hit almost everyone. Right before you go in there the fear hits you: "Will I get humiliated", "Are my skills enough?"
Personally I get that before every match, but it usually disappears the second the match starts. The more you compete, the less the jitters affect you. I've only competed twice in just under two years and run off an adrenaline high for most of the 6 mins of match time, but there's a 40yo guy at my school (former wrestler) that steps on the mat and performs like he was sparring.
My advice (you already know I'm two years into it, so take it FWIW, heh):
-A few weeks before the comp, go hard in training. Simulate the pace that you'd grapple with. I personally think pacing can be a game changer. My last comp, most of the matches I won were due to imposing an uneasy amount of physicality on my opponents; the smaller/weaker guys had 185lbs of oddly quick blubber passing their guard, the stronger ones couldn't keep up on the scrambles. Of course, I'm not saying spaz out or anything, technique is still key here. For the record, the one's I lost to got me on technique.
-Focus on your go-to techniques and tactics. There's little point expanding your repetoire in comp prep (though, if, for e.g, your bottom game sucks hard like mine, you might want to work on escapes, sweeps).
-Cover your bases in training. If you're a top player with good takedown defense, you're all fine and good until you can't take your guy down: Then what? Make sure that guard is decent enough that it isn't an automatic guard pass for your opponent when you pull it.
That's all I got.