Basting needn't be a fixation, but every 20 or 30 minutes a sprinkling of melted butter and/or pan juices helps. Be sure that the stuffing and the bird are cold in order to inhibit bacterial growth and don't overstuff ‑ stuffing expands during cooking. Here is an approximate guide to cooking times, using a 325 degree oven: if your turkey weighs 8 to 12 pounds, figure 3½ to 4¼ hours cooking time; if its 12 to 16 pounds 4¼ to 4¾ hours; if its 16 to 20 pounds, 4¾ to 5¼ hours; and if its 20 to 25 pounds, figure 5¼ to 6½ hours. If your thermometer reads 170 to 175 degrees the turkey is done. The juices should run nearly clear. When done, let it rest 20 minutes before carving.