You can start your study in semester 2 for most general undergraduate programmes. However, some programmes, like Health Sciences First Year and First-Year Law, can only be started in semester 1.
Depending on the subjects you wish to take, your paper selection options may be limited in semester 2 as some papers have semester 1 prerequisites. Details of paper prerequisites can be found on the individual paper pages or in the prescription section of the Guide to Enrolment.