Jeff,
You're doing it right.........work your way up.

ASA has 3 classes that you can shoot in with pins, I think Novice,Hunter,Unlimited.....and IBO has Hunter, Advanced Hunter and MBR.

Definitely learn the game, learn the yardages, win some shoots and you'll KNOW when it's time to move to the next class. You can have a great 3D shooting "career" if you will and never shoot in an "Open" class.
I have 2 friends who are shooting IBO Pro "PMR" who went right from the class I'm in (MBR,Unlimited) straightto Pro skipping "Open" entirely.
One of them finished 1 point behind Jeff Hopkins for the National Championship.

Make no mistake about it, when you work your way to the highest pin classes and competing you are at a pretty elite level in this game, but feel no shame in starting at the lower classes. That's what they are there for, to learn, gauge your progress and move up if you feel like it.
Like I said you'll know when you should move up, and most likely it will be to regular Hunter in ASA because those guys shoot to max 40. Realistically unless you are beating the pants off everyone in Hunter Class (IBO or ASA) keep your eyes off Unlimited or MBR for a while because you'll just get frustrated.

Learn and have fun.