Winter is the best time to cut wood for stringed instrument building. You want to get the wood harvested while the sap is down and the wood as dry as possible. In the spring, the sap rises into the wood, and a layer of new growth appears. The new growth will make it easy to de-bark the wood-which is good. But the increased sap will result in wood that is acoustically dead. Always try to get wood cut after the leaves fall, or after cold weather has set in.