Good luck with the competition. I remember my first... not that long ago actually, lol... I was quite nervous at the start, but I noticed that everyone else in my group was too. I think once you actually start sparring it all drops off. I wasn't even aware of the crowd around me.. just my opponent, and occasionally the center ref calling things out. It was a blast and I ended up placing, so it did wonders for my motivation.
Again, good luck with it, and I'm sure you'll do fine!