Aussie,
Alot of airlines like experience commensurate with age. In this region, Cathay is one.
As mentioned in a previous post, the 5 guys I know in Cathay all got in between the age of 30 and 35. They did have 3500+hrs though.
I'm not sure how picky Qantas is, but a good mate of mine who is on the current 747 classic course with QF says the average age is late 20's. Bare in mind thats Direct Entry, the cadet course running at the same time for the 744 has an average age a hell of a lot younger... early 20's... scary isnt it! Not to mention depressing for us guys trying to get a look in also!
I know of guys getting into QF later in life, mainly Ex-Ansett though, who had plenty of jet hours. But... even with all that experience, they had to start off as Second Officers at the bottom of the seniority list. Some about 7 yrs from retirement age.
Just keep on racking up those hrs as quickly as you can, and be prepared to travel overseas if needed!
Cheers