The rule of thumb these days is that Nintendo Australia releases games around about a month after Nintendo of Europe did (which means quite a few Australians import). This correlates well with Nintendo Frances date of March 14th (weirdly enough only Nintendo France revealed this date) but NOE are known for changing dates last minute

There are exceptions though. Chibi Robo Park Patrol is set to come out soon in Australia and there is no sight of a European release.
Just out of curiosity, how many Aussies imported instead, since I know quite a few who did.
I may not be Australian but would have imported about a year ago...if the Wii was region free like it was actually meant to be. Importing hardware and modchips are not viable options in my eye (my soldering arm is terrible making modchips a no-no and I disagree with owning multiple hardware).