In our school district, the child who goes to a private school to get around the cut-off date can NOT transfer until the whole grade is completed. I sent DD early (her bday is late December) and never regretted it. But I also kept her in the same school system.
And just on a side note, when your child gets to HS it is much harder to deal with them being younger. EX: all their friends will be able to drive and they won't, and like in the case of my DD she will only be 17 for her first year of college and won't be 21 until she is leaving college. Therefore, she will not be legal to drink until the last minutes of college... Just some food for thought.
The age difference may be a problem for some kids, but not necessarily. I'm a December baby, and my first school district's cut-off was Nov. 30. Since all the other kids on my block were going into K, and I'd be left with no one to play with, my mother talked them into letting me into K, and if I couldn't handle it, they'd keep me back. I was the first in my class to read, so it was full speed ahead. I didn't turn 18 until December of my freshman year in college. And it was actually nice not to have to drive; my friends always picked me up!
My d is a September baby. Our district's cut off at the time was December 31, but allowed the parents of fall babies to hold them back a year. In daycare, all my d's friends were on the older side; her best friend at the time was 11 months older than she was. She went to K at 4, and did fine. She's not into sports, so that wasn't an issue. She gave me a hard time about not being able to drive, but I think she was really OK with it. She turned 18 at college. (I'm the one who regrets not having another year with her! But she's doing more than holding her own.
Thanks everyone for your replies. I'm still not sure what to do. I'm home during the week, so half day K isn't a problem. I have to look at the contract I signed with her private school. A pp may be right, though I think I read something about giving at least a couple weeks notice, not sure. Another poster also mentioned that the township may make her stay the whole year. These are all things to consider. I don't regret starting her early, but I might regret making her transfer. *SIGH*
As one school administrator told us, at half-day kindergarten, they spend most of their time lining up. If she likes the curriculum, has made friends, is comfortable with the routine, I'd keep her there for the year (and yes, I sent my d to a private school for kindergarten because I believe that half-day kindergarten is not worth much). Moving into any grade in the middle of the year is tough; kids have formed friendship groups (almost cliques, even at that age), there's a rhythm to the class and to the day that a new kid disrupts, the teacher already knows the kids. I moved several times and had to change schools in the middle of first grade, and it was a horrible experience. I wouldn't do it unless there were no other choice (we moved across state).
You know your daughter and her maturity level. She may be fine in kindergarten another year; my d would have been bored out of her mind. Yours may prefer the maturity.