From someone who has had a sprained wrist, it takes about a week for the swelling to completely go away. After 3-4 days, I could play BB, but with a brace. In a week, the lingering pain completely subsided, but there was still discomfort when alot pressure was applied to my wrist. It took about two weeks for it to fully heal.
So, with that saying, Splitter should be close to 100% by round 2 of the playoffs, when the Spurs will need him most. He will be wearing a brace obviously, and its on his off hand. So I don't see any tremendous drop in his game occurring from this injury.