Didn't you have to do a tech inspection of the car for your event? I've attached a copy of the tech sheet our local BMWCCA uses.
The biggest benefit I would say you have from doing autocross is "vision". Looking ahead is super critical for autocross and it is just as beneficial for tracking.
Its your first event and there will be a lot to take in. Know your limitations and don't push yourself past those limits your first time out. I went in with the attitude that "I don't know, what I don't know" and just tried to absorb all I could from my first round of instructors.
Hydrate, hydrate, hydrate! Seriously.
Have a great time and don't feel bad if you book your next track day before you leave the track...