Like Pat said. With any wood, do what he says. I also look for small differences in the tree and try to take staves from the high and low side, because if you take them from the sides, they will warp laterally instead of into reflex when they dry. I have never found a tree species that won't do this in a small sapling.
Also, look the tree over carefully. Often as not there is really only one good stave in a 3" tree, and you'll ruin it trying to get 2. And, like, maybe there is a great stave on one side and a good candidate for decrowning and backing.
If you do split them, look it over carefully and chose your splits well. I even kerf the edges with the tip of my small chainsaw, or drill a few pilot holes in case it tries to wander.
One thing I'd certainly do is make a bow now, and then watch in excitement as those saplings grow to 6-8"" trees! You can even groom small branches off them and stuff!
