Both of the SCCA regions that I autocross with have specific course walks for novices, provide pro's to ride along with novices during competition, and even can pair you up with a more experienced worker for a work assignment.
In my opinion, its very easy to jump in as a novice, and compete your first time. As a novice I'd recommend making sure you walk the course a couple times and/or have a pro or instructor ride along during your first run.
Parking Lot Hero
2008 WRX daily driver
2003 ZX3 23D Autox Car 42 FSP
"Hella Functional - Raced, Not Hard Parked"