Got the courage today to hit submit and do the tests - nice to have it done!
A few notes for those concerned about struggling on the tests - the tests are adaptive which means if you get a question right it gives you a harder one next, so you're supposed to feel challenged throughout - the difficulty of the questions is tailored to your own skill level this way. So everyone should feel they were tough as they should be around your individual limit. It also means it is hard to predict how well you do, because it's not just a simple "6/12 score" for example.. so try not to stress!
As for when we find out, last year 2 days after the deadline I was told I'd passed the online tests (aka my status changed to 'longlisted'). I'd expect similar this year. I don't believe you find out immediately if you fail anymore, as it depends how well everyone else did as to what the cut-off is. From previous years stats it seems to chop off the bottom 30% or so of applicants.
I think this stage would be the worst to fail at because then all the hard work on the app doesn't even get read. Myself I'm nervous about the maths one as I know a lot of stupid mistakes that I made, but just doing my best to put it out of my mind until after the deadline. Just got to cross my fingers (and toes). Good luck everyone!