In dec normal part time jobs are not much, but as per my knowledge hotel & tourism industry are having many temporary openings. Please use search term "Part time jobs Sydney" on google and you will get many sites.
I assume you are talking about non-professional job, such as waiter, kitchen hand, receptionist and so on...
If that is no, stop reading, unless you don't mind to work in this field while waiting for your interview or coming professional job since there are not much job vacancy at the end of year.
If that is yes, you shall apply now, since most university student are buzy with their assignment and exam's study. Many of them quit their casual/part time job and you will have higher chance to land one, try spread your cv. During christmas or public holiday u get 2x wages (around 30-40 bucks/Hour at McD or Nandos or this type of working places)