I've got my stage 3 on the 25th Jan too, see you there cpteffron! I managed to pass my last minute stage 2 test so if anyone is wondering if its possible, it is! You can't really practice for it, just answer quickly and accurately. Put as bluntly as I was advised beforehand, you either can do it or you can't. It may seem harsh but it should give you confidence if you pass.
I do have the same question as cpteffron, it may simply be a defined time period to allow people to organise transport to and from the CTC and the interview itself will be at some point within that period. The rest of the time you just wait maybe? Again, any pointers would be greatly appreciated either on here or as a PM.
Regards