HI L.---Our oldest has a late Nov. birthday. She didn't start preschool until she was 3, almost 4. She was accepted into a Head Start program because she was very shy and anxious. I digress a bit, she is now 26 so there wasn't an much of an emphasis on preschool then as there is now. Anyway, she was fine once school started. No signs of anxiety like she showed in testing. BUT...this is the important part. She was our first and even though she was and is a great, smart student, we held her back for social and emotional reasons. Little girls can be really evil to others later in grade school, jr high and high school. Our concern was for her at that stage of her life.
But then, our youngest has a late sept birthday. We moved to Illinois when he was 4 so he was not able to start school until he was almost 6. He was reading before he started kindegarten and graduated with honors here in Clarkston.
My point is that I think it's good to let them be little for a while longer. She has lots of time to be a grown up. As she gets into her school career, she will be identified and put into advanced classes. In high school, they have all kinds of AP classes that give them college credit. She will have advantages being the oldest in her class rather than the youngest. I think those far outweigh giving her challenges at 3 years of age. I think waiting will set her up for successes that she might not have starting school early.
Hope this makes sense. Good luck. D.