depends on the school. we applied for the gov't voucher in january and once we received it in May (?) we sent the application to my son's school. he was admitted in september. we LOVE his school and would highly recommend it to anyone. it is a local school but they have a lot of expat children. the language of instruction is cantonese with a few classes in english.
we only went to see a couple of kindies in our area at the time and knew instantly when we went into his school that that was the school we wanted. it was very laid back, not stressful and the kids looked happy!
i know a lot of parents really stress out about finding a kindergarten, but i think it is really unnecessary and only plays into the system. it is, afterall, just kindergarten... it's not going to affect their entrance into Oxford or Cambridge or something like that.
again, just my opinion, and i know there are plenty of people in hk that disagree with me on that...
good luck!