Boone, like Phil said, best to wait for a few days to be sure you don't get a re-fermentation from the added sugar. The addition of potassium sorbate should guard against that but it is not always successful. One other suggestion I always make is to bench test before you sweeten the whole batch. I also suggest under sweetening just a bit because it has been my experience that wine tends to sweeten slightly by itself.
Good luck.