Re: how does the timetable work?
I guess get your stuff ready, your contact details, TFN etc etc, know your way around USyd and where to enrol, and the UoS that you want to do for Sem 1 and 2 rather than deciding on the day.
Its okay but the USyd Enrolment and UAC website does provide some information, and if in doubt, try using the Search function for similar threads. If that doesn't do anything, ask.