You will get a lot of people telling you not to rush her. However, is it really rushing her when one school says October, another December, and yet another July 31st? Why is it that the schools keep pushing the date around? It has only been in the last 15 years or so they started moving dates.
I was 17 when I graduated because my bday is December. The cut-off was January. I went through a whole semester at a TOP ranked private school before I turned 18. I did fine. I even did better than most kids as I was in the college track and not the "easy academic" track. This meant that I had all accelerated classes starting in 7th grade. Oh, and did I mention that I was in a private school from K-4? When I left the private school I was academically a year ahead? We used the same text books in 5th grade that I used in 4th. When my parents moved to another school district during my 6th grade year, they were using the same books I used in 5th and 4th grade.
I stopped trying as hard because it was all too easy.
My daughter does well in school, too. She needed to skip 1st grade, but the principal would not let her. The VP wanted her to, and I wish I knew my rights back then. I would have taken it to the school board. She completely lost the love of reading and has learned that the schools don't care so why should she? She is in the Talented and Gifted classes and does well, but seems to have lost that sparkle she had for education. I was recently told by the new VP that they don't like to create "Doogie Housers". UGH! My response: Tell the parents of the 18 year old math professor who is getting through to kids her age that other teachers never could, that they were wrong to accelerate her.
I feel that if she can get straight A's if you hold her back, she has the capability to get straight A's if you don't. Waiting that extra year will not change her capacity to learn and get good grades. And when it comes time for the body changes, don't let people tell you she'll be off from what all other girls are doing and acting. Again, my daughter is case in point. She is the 2nd youngest in her class and yet she was the 1st to develop boobies and get her period. Yes, she is the envy of all her female classmates and gets made fun of by the boys. (She is in 5th grade) She hates it and wishes even more now that she was able to skip 1st grade because then it wouldn't have been such a big deal.
Many people here will say not to rush it and enjoy her at home another year. I personally think that is selfish because it is done to satisfy your needs and does not meet the needs of your child. Our goal as parents is to get our kids to not need us an become responsible adults. I don't believe you are causing your child to grow up too fast if you are trying to keep her educationally challenged.
Remember this: KIDS WILL RISE TO ANY LEVEL OF CHALLENGE THEY ARE PRESENTED WITH. If you set the bar low, they will only meet that. If you set the bar high, they will meet that. The first few years sets the tone for the rest of her life. If you feel she is academically ready for Kindergarten material, then go for it. You have rights, too. Go all the way to the state BOE if you have to. I get sick of how it seems like only those kids who are having trouble in school get all the benefits. The kids who excel have the same benefits, too.
My daughter cried every day after school for 2 years because she was so bored. I wish I could change that. I know better now what my rights are.
I would like to encourage you to get her tested. If the end result is NO, homeschool her and have her tested again next year for 1st grade and skip Kindergarten. Kids are sponges. They will learn what ever and how much we give them. Sept 30 .... in some schools she will pass and other not. So, obviously there are those who feel kids that age can do well in school.
My last point is this: from my experience, the reason the age gets higher is they are teaching more things in Kindergarten. They are able to do this because they are teaching things in preschools to get kids ready for Kindergarten. Preschools boom because there are many moms who work and need the childcare. Parents don't spend as much time with the kids teaching them at home what they need to learn and rely on the schools to teach them. I see it every day at school. The ones who excel are the ones whose parents work with them and encourage education.
Think about this, there are many private schools who take 4 year olds in Kindergarten. Those schools would have taken your daughter LAST year. Private schools outperform public schools for many reasons. Please, I encourage you to don't take the easy road. Instead, think about all the wonderful benefits of educating your child and teaching her to never accept the easy way. When she goes to college, she will be with kids who are her age and some even younger. She will also be grateful that you prepared her for the challenges she will face, too. Raising kids isn't just about hugs and kisses, it is also taking the responsibility to recognize the academic needs of our kids and helping them there, too. Don't settle for less or you will teach your kids that as well. My response may not be the popular response, but if your child is ready for Kindergarten, then she is already above the average, popular response. Why keep her there? Go for it!
PS> Oh, yeah, the reason for the maturity level differences? Parents keep holding their kids back! No wonder! You have older kids who should have started but didn't. They are throwing off the "maturity" curve and perpetuate the problems for the rest of us who have kids that are capable of handling everything.