It's all about your position on the list and the age demographic of the Captains. If you're at the back of the hiring boom and the left seaters are mostly in their 40s then you've got a long wait ahead. LCCs are usually quicker because of turnover of pilots as they move on and expansion.
At the moment QF should be a quicker than normal (for them) upgrade as their Captains are mostly in their 50s and they're hiring again in big numbers. Someone joining now might sit for a few years twiddling their thumbs and then move up fairly rapidly.
Jetstar and Virgin Captains are mostly younger as they joined in the early 2000s got quick upgrades as the companies ramped up and are looking at another 15-20 years until they retire. Around 15 years ago Virgin Blue had less time to upgrade on the B737 than Sunstate did on the DHC8.
Air Canada and Air New Zealand were the longest at around 20 years but would probably be a bit less for someone joining today.