A few thoughts:

1) Seeking a process -
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a process for determining if early entry to Kindergarten would be appropriate... there is no such process at our local school
You may have read this elsewhere on the forums, The Iowa Acceleration Scale ( IAS ) is a tool which outlines a process for evaluating the appropriateness of a full grade acceleration. If your district is unfamiliar with the IAS, you may wish to mention it to them. The Acceleration Institute offers Policy Guidelines to facilitate the establishment of acceleration policies within school districts.

2) It is not wholly true that your state does not permit early entrance to kindergarten. Although mentioned in a recent post: "we are in California... children under 5 are not permitted to attend K", according to this State Policy summary, for CA as presented by Acceleration Institute:
Originally Posted by State Policy summary, for CA as presented by Acceleration Institute
"The governing board of a school district maintaining one or more kindergartens may, on a case-by-case basis, admit to a kindergarten a child having attained the age of five years at any time during the school year with the approval of the parent or guardian, subject to the following conditions: (1) The governing board determines that the admittance is in the best interests of the child. (2) The parent or guardian is given information regarding the advantages and disadvantages and any other explanatory information about the effect of this early admittance."
If your child misses the cutoff by only two months, it appears that starting kindergarten after those 2 months have elapsed may be an option, and your child may not need to wait for the next school year. It appears that at age 5, a child may also be admitted to the first grade.

When advocating, it is very important to be familiar with your current State laws and district policies. Because these can change over time, you may wish to print them and keep them in a file, ring binder, etc, arranged by year.

3) Other options available
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My husband feels strongly that if they say no, they should have a plan of what would they do to accomodate him. They literally have no alternative at this time and freely admit that they have no options for him
A person "feeling" something is not compelling, nor does it obligate the other party to take actions you may wish to see them take. You may wish to do some research on acceleration. Review your State law. The Acceleration Institute has gathered many resources together in one place to make this much easier for today's parents, than it was a decade ago.

One resource offered by the Acceleration Institute, the Iowa Acceleration Scale, is subtitled: "A Guide for Whole-Grade Acceleration K-8"... and single-subject acceleration is mentioned briefly in the Manual on page 104, and Planning Record page 3. Some schools may use the IAS to prepare a complete record of a student's scores and "thoroughly discuss the case and to consider other curricular options and recommendations for the student." (Manual page 34)

4) Next steps
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if he can't go to K early, what are we going to do?
You've received valuable information from several posters upthread about possible future acceleration strategies.

5) Have you thought ahead... are you well aware of tradeoffs (possible downside) to early entrance? There are several threads on this, including Grade skipping tradeoffs. Here is also another thread on what to ask about early K. I am a strong proponent of acceleration, and believe its success is enhanced when parents are well-informed, anticipate and are prepared for trade-offs, and have realistic expectations.

6) Linking to your related thread, Help me write compelling points in letter... as this may be helpful to future readers.