Do it man! I've got to say I'm really in the same boat, debating if I'm going to compete that is. There's a tournament out here in July I want to compete in, but I'll only be training for about 3 months when it comes around. At first I thought I would just skip it, but I'm starting to see improvement in my game and the guys at the gym (Dave that's you especially) have really been going out of their way to help me grow.
Here's what it came down to though... I love jiu-jitsu and eventually want to be a tough competitor and the only way to eventually become that is compete. The way I am looking at this first tournament experience is just that, an experience. I'm a white belt going into a beginner's division with nothing to lose. If I go in and lose my first match, well that's just life. I'm using this to see what games people play in the beginner division, how tournaments go, to see my friends/coaches compete and just to have fun. Don't get me wrong though, I'm working my ass off so hopefully it doesn't get handed to me in the tournament
I'm not sure if this applies to you or not, but for me getting to compete in my own weight class is going to be a HUGE difference. I'll be competing in men's beginner roosterweight (122lbs and under). I'm around 115lbs right now for me I almost always give up AT LEAST 30-40lbs when rolling in the gym so I'm really excited to see where I stand with guys my own size.