I'd start it from black. Start it with Scorched Brown, then a layer of 50/50 Scorched Brown and Snakebite Leather (which sounds like it might be close to Bestial Brown, but it really isn't), then a pure layer of Snakebite, followed by a layer of Bleached Bone, highlights of 50/50 bleached bone and white; and edge highlights in pure white.
You'll always get more definition from a black undercoat, in my experience-- from white, it's ultimately an exercise in going back and lining-in details and using glazes to get shading, which is a lot more time-consuming to get right than just doing a several-stage layering method.