Here is the process in brief:
In the late winter (this year from Jan. 10 to March 4) is the application period. Schools offer tours and zoned families as well as out of zone families who want to try for a spot at the school must apply for a seat. This is NOT REGISTRATION. It is a head count (although a required one). The school has no idea before this application period of how many children might attend in the following year. It is also a time to build a wait-list of families who want to gain entry from outside of zone if they have seats left over.
From March 21 - March 25 the schools will notify in zone (and sometimes out of zone families if they have enough room) that there are spots open for them in kindergarten.
From March 28 to April 15, they schedule times for the families to come into the school with their child, their proofs of address, birth certificate and immunization records to PRE-REGISTER.
It is common practice for schools to save some small number of seats in reserve for in zone families that had no idea of the process, or for families who move into the zone after the application period is over through the spring and summer.
It is also true that the G&T process as well as the wait-lists for Charter and Unzoned schools move throughout the spring and families who have pre-registered at schools with register at the other programs and their seats will become available at the zoned schools and the wait-lists there will move. This is an ongoing process through the spring and summer.
What if you misunderstood the application process and didn't apply at your zoned school?
You will probably be placed on a wait-list at this time (don't panic), just because you are in between processes. Keep in touch with the school. It is likely after the first wave of registration happens that you will be brought in to register.
What if your zoned school says that they don't have room for you?
This has been a problem in Manhattan and other boroughs for a couple years and in Sunset Park in D15 last year. The popularity of the south slope schools is proving to be a problem for zoned families in PS 39 and 107 this year. Check out insideschools.org report , as well as gothamschools.org report from last year.
I asked Manhattan school guru, Robin Aronow, what happened last year for families squeezed out of their zone. And this is what she told me:
"The way it has worked in Manhattan is that after April 15th, when pre-registration is over, the wait-lists will start to move. BTW 40 is not a lot on a wait-list (unless families tend not to go to private school or G&T). Sometime in May, if a family still remains on a wait-list, the Office of Student Enrollment will make an alternate offer to a school in the neighborhood that has room. The family can remain on the wait-list of the original zoned school until October of the start of kindergarten. If the family has still not come off the zoned school wait list by October 1st, the original zoned school may take no more students for that school year and everyone else who moves into the zone goes to the bottom of the wait list. Prior to September of 1st grade, if there is space in the original zoned school for 1st grade, then families who were placed elsewhere will be called back in order of their original lottery number. It is possible that there will still not be enough room for 1st grade. However, my guess is everyone or almost everyone will be placed by September of kindergarten and most likely by 1st grade."