The only times Australia came last in releases was with Red & Blue and Black & White, and they did get Gold & Silver before the US. I'm sorta speculating the pattern will be the same as most games - Japan > US > Australia > Europe.
In fact, here's the patterns based on the last few games (I'm counting Japan out since it's always first):
Red & Blue: US > Europe > Australia
Yellow: US > Australia > Europe
Gold & Silver: Australia > US > Europe
Crystal: US > Australia > Europe
Ruby & Sapphire: US > Australia > Europe
FireRed & LeafGreen: US > Australia > Europe
Emerald: US > Australia > Europe
Diamond & Pearl: US > Australia > Europe
Platinum: US > Australia > Europe
HeartGold & SoulSilver: US > Australia > Europe
Black & White: Europe > US > Australia
Black 2 & White 2: US > Australia > Europe
Notice how it's almost the same pattern? Australia usually almost always ends up in the middle. Even though some games had a big few months' difference with the international releases, it often ended up with the same pattern except for Red & Blue, Gold & Silver and Black & White.
That makes sense.
Japan gets them first because it's where the games are made.
The US gets them second, because translating from Japenese to English makes sense.
A delay between the American release and the Australian release makes no sense, but it's there.
Then the translation to the other European languages begins, so the games can be released in Europe (in all languages at the same time).
More than likely I'll get the games the day before the release date. I think Diamond might've been the last Pokémon game I bought on the release date, all others I bought before the official release date (with Black being the exception, but I got white the day before the release). I even got my 3DS the day before the official release (does that make me a very early adopter?).