If the stave is green, I drawknife my way down to 1 ring above the one I want for the final back, then shellac it well. Unless the stave is super snakey, has alot of twist, or has growth rings that go thick-thin from side-side, I'll even layout the bow based on the grain in that ring.
On that ring, I'll pencil everything in, narrow to final width, thin the belly, and dry it. When I feel comfortable that it's dry, I'll chase the last ring with a drawknife, scraper, and sandpaper, then proceed right into tillering.