I'm responding from the perspective of having a daughter diagnosed with dyslexia and dysgraphia in 4th grade after asking questions since kindergarten. She didn't struggle to read, though showed no interest until kindergarten. I estimate she went from zero in October to ~4th grade level by December.
KJP, I think you have a good plan. I might add: ask if the school administers something like DIBELS or AIMSWEB, and if they do, get the results when the tests are done. These are good, first cut screening tools, but at least the teachers in our school don't really understand them.
Also, for your discussions with the teacher in mid-fall, you need to keep in mind that the party line is that reversals are normal through second grade. It's the party line because it's true. However, they should decrease through time. the likelihood you have a kindergarten teacher who would view anything as problematic with regards to reading and writing at this point is very small. Instead, I'd ask things like "does he delay getting to work on writing assignments but not other tasks?" "how much progress has be made in X?" etc.
Keep a copy of things that come home with the return date on them. Watch not for the reversals to disappear, but for them to decrease dramatically. If you do end up with the Eides or someone similar, these will be useful examples.
