Ok, here's my take on it. I'm a homeschool mom.
I've watched the public schools push certain skills and academics to the lower and lower grades all the time. Every year, they expect more and more from the younger kids. Moms post to this board all the time about how stressed out their kids are and how the teachers are putting pressure on the kids for more, more, more. Some even have homework, and quite a bit of it, in the lower grades. Meanwhile I don't see the california schools exceeding as far as standard test scores.Indeed, they are on the bottom. I'm not saying this to be judgemental, I'm saying that the push for more academics at lower levels is not the answer. If it was, the state scores would reflect it.
That is a BIG change between private k-Montesorri and PUBLIC SCHOOL grade 1. In many of the schools, Grade 1 is expected not only to be reading and writing pretty well, but also spelling, and some are even introducing early concepts of algebra.
As a teacher I saw in my own children that there comes an age when the brain is "ready" for formal writing instruction. Age 6 is a good age to be "starting" writing and spelling. I tried, as many other homeschool moms I know, to start my son at formal letter formation by age 5. Nope. It wasn't going to happen. He wasn't emotionally or physically ready. If you let kids mature enough to be physically capable of the actions you are asking them to perform, you can avoid much stress, havoc and learning blocks. I am assuming that they are beginning formal writing in k grade- if the kids are 6 in that grade?
My opinion is to put the child in the grade appropriate for his age, grade K.