Relax. Take each step at a time because anticipating further than the speed that Administration can work just equates to lots of impatient waiting every day. But since you asked, here's the general schedule of things:
UAC will notify you of your offer(s)/non-offer. Main round offers are released on Wednesday January 19th 2005, and the next day in the papers. It's the notification from UAC that's important; the newspaper is for show purposes.
You will reply with your acceptance/declination of the offer(s) - UAC will tell you how.
If you accept, the relevant uni will send you the procedure for enrolment and other related details. This will include formal enrolment as a student, program/subject selection, and fees, etc.
After all that is done there will most likely be orientation days and programs. If your uni has a 'Getting adjusted to uni/study' program or similar, I highly recommend you participate. You'll get the chance to meet (or at least spend some time) with people who will also be beginning their studies, even doing your course/subjects. Most importantly, I believe, is the support with anxieties with beginning tertiary study; as well as getting to know the ins and outs of the uni and its structure. Otherwise if you're doing a bridging class it might be enough as orientation, although it's focus is obviously to teach a subject.
And then your first class begins. Usually a lecture, where you are spoken *at*; Sometimes a grouped lecture (ie: different but related courses being taught common/introductory things together); Sometimes a tutorial, your classroom setting, where you are spoken *with*; and Sometimes depending on your course, laboratory or workshop, which is practical to the subject.
Then it's study for the rest of semester until you do re-enrolment again - which is too far to think about (see initial argument above). Simply, re-enrolment is informing your uni you'll continue your studies for another semester, and another semester...until you graduate.
And, unless you are transferring from your course to another one (or some other rare circumstance), your UAI will be irrelevant for the rest of your life! (But gee yours looks pretty enviable.)
-andy