It sounds like you are in a very good place - 80 - 90% at this point are great scores, and I think roughly what my DS was getting at that distance from the test. You should certainly have enough time to fine-tune the test technique and speed to boost those scores up into the 90s more consistently, which is what you ideally want. It's good to bear in mind that being good at maths and being good at maths tests are two rather different things, so test technique practice is really useful. Also, the consortium maths paper is apparently really easy, so being brilliant at maths won't necessarily by itself get you a high score - there won't be questions that allow that brilliance to be revealed. My DD wrote the consortium paper last November and reported that there weren't even any questions on fractions. So you need to be super-solid on the basics and really, really alert for silly mistakes, which is where the marks will be lost. The VR is the tougher paper, so do lots to prepare for that to build up speed.
Music - my DS got an academic place, but apparently would have been given a music place if he hadn't got music. This astonished me - we'd really only done the music aptitude test as a sort of test run have the experience of sitting in a hall doing a test. At the time he had only just done his grade 2 piano, and I was cursing myself for not putting an orchestral instrument in his hand 5 years earlier. So it seems that (a) piano is fine and (b) high grades not necessary - they seem to judge your performance according to the level you are playing at. I suppose it is supposed to be a place given on musical aptitude (ie potential), rather than the fact that you've been going to lessons for however many years. He really enjoyed the music audition - came out beaming, and said, "that was fun!" - and played a piece that was very 'him' rather than extremely impressive. So I think make sure your DC plays something that they like - it will be easier for them to look like they so actually enjoy music!
Applying for DAO so that you can do their tests first - well, if it fits in with your applications anyway, this is great. DAO was our second choice (lovely school, almost impossible for me to work out how DS would have got there, but we would have made a plan if that's where he ended up) so DS did do the DAO music, VR, maths and English before the consortium. I agree with Daogroupie - it's a super practice run - but I wouldn't have used one of my very precious three allocations on it if it wasn't also
a school I would have seriously entertained my DC going to. With three choices only, I'm not sure anyone can afford to use one as just an opportunity to practice tests.