Good luck. I hope that this works out well for your ds.
Based on what you have shared, I would expect that you may have more acceleration in store for your ds in the future, though. My dd11, for comparison, has a Sept. bd so she started K just before her 5th bd. She then skipped one grade (5th) making her just a bit older in the grade she is in than your son would be if he continued on the same track. My dd is not likely as gifted as your son yet the skip was a pretty good choice for her. She is still doing very well academically and it is not too much for her. I would imagine that a more highly gifted child would need more than she has.
Perhaps later down the line you can look at early college entrance if more skipping w/in the primary & secondary years isn't a good fit for him.
Let us know how it works out.
