It's a tough decision. I don't know if there is a right answer. For our DS4 (almost 5) we are in the process of planning to skip K and go to first. that won't at all be enough for him either....but for us I would rather start with that and do subject accelaration. And maybe even having him go several grades ahead for some subjects, but still have him in a grade that is a similar age with peers. Still there are some caveats, but I am hoping that will work with him for now. Who knows, you live and learn...most of the time at least.
good luck!
