Agree with all of the above.
If you want to improve your chances of seeing one I would suggest to make sure it is astronomically dark (sun 18° below horizon or more), which currently in Sydney means after 20:50 - better still, after 23:00 when many people switch their lights off. It does make a difference!
Whichever one you pick from the suggestions above, you will see more the closer it is to zenith. In a city environment, particularly if close to the sea, anything below say 60° altitude may remain hidden in the haze...
If you have trouble finding Centaurus A (NGC5128), try to locate NGC4945, on 'the other side' (4° SW) of Omega Centauri - this galaxy is often a somewhat easier target than its more famous cousin, AND it has a bonus in the same FoV: NGC4976 (mag. 10) which you might be able to see if the conditions are really good.
good luck!
