^ My best friend works long haul for BA (me? I'm VS all the way...) and she also said something similar about having to be around years to get purser as it's done on seniority but one of her fellow crew said they'll have to change that now as you can't discriminate on seniority ((some lardy-da EU law!))
Not about Qantas i know but it might help your decision if you know you might be able to become purser sooner!