You've received great responses above. The student, the mix of classmates, and the teacher can create very different results.
I am highly motivated to continue advocating for early entry
Possibly not the perspective you're looking for, but some may say learning about
advocacy may be the first step. Laws, policies, factual/unemotional presentation, active listening, gently probing questions, developing options/alternatives, documentation...
also-I'm terrified of the possiblity they won't approve it
Why does this terrify you? How does your son feel about early kindergarten? Looking at a
previous post, some may say that early kindergarten will not alleviate the emotional issues of anxiety/depression/highly explosive expressions at times. A school may even blame any such issues on immaturity especially if a child is accelerated (either through early entrance or a grade skip). This is not to dissuade you from acceleration, but to mention that you may wish to learn all you can about these issues and continue addressing them at home. Have you looked into books such as
The Explosive Child,
Make Your Worrier a Warrier,
Searching for Meaning?
If you have a child was beyond Kindergarten academically, but they attended at 5, how did it go?
While a child is adapting to the routine and getting to know the other children, s/he may be positively engaged and mentally occupied. This can give the teacher the opportunity to observe the child's relative strengths/weaknesses and make recommendations. A child will typically not begin to develop underachievement from lack of academic challenge in his/her school day at age 5. If your child wants to learn something in an area of interest at his challenge level outside of school, would you be able to find resources and/or enrichment activities/classes?
