I think that it probably past K. But, I would not necessarily advocate skipping K with a kid who writes like this and has occasional reversals, mixed caps, etc. It sounds to me like he needs a bit more phonics training which he would get in K. From my experience, kids who teach themselves to read at a young age do not know phonics well. This can cause problems in spelling and reading later on when they don't know the words and cannot sound them out. You may think about doing K and 1st and then skipping 2nd.