I have a kid with aspergers who was very advanced at reading and math before starting kindergarten. It is encouraging that the school said they will give him a full time aid. I am amazed at that. So maybe your school is better funded and will look at your child as an individual.
We were not expecting the school to actually teach him anything at first, but we sent him for the experience and social stuff. By first grade we had to pull him out to homeschool him. The school environment had turned out to be toxic for him. Very negative social interactions with some quite aggressive kids in a chaotic classroom. And yes. In kindergarten he was expected to sit quietly for rug time and learn letters and basic words with the other kids. Excruciating after a while. He was eager to participatebut very fidgety and the material was terribly boring. We made the best of it for a while, but it didnt work out.
That's not to say that it can't work out for you. The school has his weaknesses well doccumented, now, make sure they also document his strengths. Half day is nice. I wish first grade was half day too, and second... Full day was such a time waster.
So, document his strengths. And, the full time aid may be a saving grace for him
