What's the usual age to start preparing for these? DD is just finishing year 2, so I had assumed it wouldn't be until year 4, but is that complacent? Also, is a tutor necessary or will practice papers and general smarts be enough?
For context, DD has been doing year 5 maths and has a reading age well ahead of that (the school tested her last year and said it was 12/13 then) so I think she would be capable of thriving in a selective school without needing to be hothoused, but if she's going to sit the test I'd want to maximise the chances of her passing.