Seems they don't have an exact deadline for the P1 enrolment. This is my case:
May 08 submit our enrolment with profile
Jun 08 got interview
Jul 08 got offer
Sep 08 went to school happily:)
As far as I know, they still got children on waiting list when we're offered an interview. So, they'll try to give you an interview if you submit your enrolment I guess!
My son is on the waiting list of ASP and YW. And, accepted by TT. But, one day, my son told me that he likes the school just next to YW. So, we will try.
I think some difference from this 2 years. My friend wanted to submit the application form on 31th Oct,2008. But school rejected him and set the deadline this year. Of course, you can try.