My friends got in peak during the 6-week holiday. Funny thing was i called them a week later and the person who picked up jotted down my details and said they call me back... which they never ever did.
Oh, i also remember trying to join in year 11. My school was going ahead of them ,no idea how that happened, they told me that it would be a waste of time for me.
My friends also told me there are like 'factors' which would increase your chances of getting a seat there.
1. Live near or at Canley Heights
2. Good ranks in school
3. Also attend Ngo and Sons Tutoring
4. Get your parents to do the talking on the phone
5. If you do both physics + chemistry
6. How far are you in the topic
7. What time you call, because you want to speak to him directly, not to someone else and getting 'call you back'.
So yeah, good luck.