I rang the ANU hotline and asked about enrolment for people staying on campus or uniLodge etc. and they said that we can actually enrol on monday 15th if we really want to, just as it will save time and then you know exactly which classes you are doing and your timetable and are free to enjoy o week.
The person I spoke to said that even though the day is allocated to a particular selection of surnames, if you explain that you were unable to make your allocated day in the previous week because you live far away that they'll be fine with it.
Just might be a good option for some, especially if you require status for previous university study or just want a load off your mind