I pre-ordered a 22 lb. (whole rib roast) prime rib roast for Christmas from my butcher which consists of the first and second cut roasts. Some recipes I am reading call for a quick sear ( either at 450 deg oven for a few minutes or in a hot pan) then slow cook in a 200 deg oven for 8-12 hrs or should I just sear then lower heat to about 325-350? Also this is the other problems. At a low temp I have no idea how long this Behemoth will cook for. Guest come over at 2pm to eat at 3 so what time should the roast be started? This is an expensive cut of meat so please help!!!