Yew can handle a bit higher EMC percentage than most woods before taking set. While hickory needs to be really dry, yew can withstand a bit more moisture. Still, you want the wood to be of adequate moisture level, and at EMC at all times. Without knowing how moist your piece of yew is, we can't say whether is needs to be dried more. Determine the EMC in your situation, and see if the stave has reached EMC (i.e. measure weight loss). If that EMC is around 8-11%, you're good to go.