I've been competing for over eight years and I always feel nervous and like I'm not ready.
That said, my first piece of advice is to sit down and have a frank talk with your instructor about exactly how much this is going to cost you. Showcases can get to be VERY expensive, and you don't need to be adding sticker shock on to your nerves.
If, after he's disclosed and explained the costs, you still want to do it -- then go for it! You have to start some time! I did my first inter-studio competition, where a couple of local studios got together, after I had only been dancing for about three months. I was nervous, but afterwards I realized I had had so much fun that I became hooked on dancing and competing for life! Since then I've had several amateur partners, plus have done Pro/Am with three different teachers over the years.