As Gonuts says, all the details are already in this thread. Just prepare for the initial test by sharpening up your basic arithmetic to be quick and accurate with your calculations. Time pressure rather than the difficulty of the actual maths is the challenge. Johnson717’s post number 1244 about the aptitude test explains exactly what’s involved in stage 2.
I don’t think my progress has been especially fast. I exchanged contact details with a handful of applicants at the initial test, and the ones that passed all got called through to the apt test within a similar time. I haven’t heard from anyone that’s been asked to the 1st interview yet though.
I’d appreciate it if anyone who had the apt test in late Sept/early Oct lets us know if they get invited to the 1st interview.