I also wanted to mention the social aspects of skipping. When I skipped 1st grade (many many moons ago and with minimal planning or prep on anyone's part), I didn't have much trouble adjusting to the academics; I was at top of the class within a month.
But I had a really hard time feeling like I belonged socially--there were already friendship groups formed and I had trouble fitting into them. This is probably very similar to what happens when a child moves or switches schools. And I'm guessing it is harder on girls who seem to be more political and cliqueish than boys. At any rate, I would suggest planning ways to stay in touch with his old friends and ways of connecting with his new classmates before he starts school next year. If you have a friendly face greeting you in your new class, I think that can help ease some of the first day jitters.
Good Luck!
