Well, on a normal session, they give you 3 time runs before elims. With the turnout expected to be at 300 for Saturday, don't expect more than two and only count on one time run, plus elim races. I only got one time run at this event in October.
You're better off running Friday night if you are going for the first time, since you'll get your 3 runs for sure and you won't have to worry about the added stress of competition right off the bat.
They hold 6 of these events during the year IIRC (3 street muffled like Saturday, and 3 open comp).