The exam committees for next year have already had their first meetings I believe (if not they are in the next few weeks). This is based on talking to the Head Examiner for Modern History a number of times.
They don't usually have the CSSA etc trials.
In fact a couple of years ago the same questions that were in the CSSA Ancient Trial reappeared in the HSC exam the same year (interestingly I thought the CSSA trial was awful for my students but loved the HSC - yet they were the same questions but they knew a lot more in November than they did in August).