Bolo - Depends upon the Federation in which you'll be competing. I believe that NABA allows you to compete as a novice until you win an overall title in any competition - regardless of age. Check the Federation's website for some advanced info, but all disclosures will be on the entry form you'll need to submit in advance of the show anyway.
If you've never competed before then why not just do the novice? You can use this show to workout your posing, tanning, pre-contest prep, etc. with less pressure. Plus, you'll be nervous as hell!
I had attended tons of shows before actually competing and I can remember sitting in the audience saying to myself "Damn, I could walk up there and take 1st place right now!". But, believe me, it's way different when you're actually up there!