The DoE has set some dates for the new year.
The application period for K begins on 1/22/13 and ends on 3/1/13
This is not a first come first served process, so don't freak out.
You apply in person to your zoned school and any out of zone options that you
want, because you need to bring your proofs of residency and child's birth
certificate in person. As the process stands now, you can apply to as many
schools as you like. It is not on a central application, none of the schools
know or care which school you like most and you could get multiple offers to
several schools.
Placement offers and "pre-registration" will happen 4/8/13-4/26/13.
You can only be registered to one school at a time, so if you register at your
zoned school and then hear a week or month later that you have an offer
somewhere else - when you register for that new option it supersedes your old
registration. Let the previous school know that you have released the seat so
that they can offer it to your neighbors on the wait list. You will attend the
last school that you have registered at.

Charter and unzoned schools usually do their lotteries at the beginning of
April. Unzoned schools usually have prek classes, charter schools usually don't.
Check out the schools' websites about what you need to do for them.

We don't have definite dates for prek yet: early March is when the application
period begins (you fill out one central online application with all your ranked
choices). Early April will be the deadline and offers will be made in early
June. Families will "pre-register in mid June. Hold tight for more info in the
new year.

I have information on the tweaks to the Chancellors regulations here: