Cooking time adjustment for smaller cut of meat

Don't worry, pork shoulder is very forgiving. If its bone in, then it's done when the bone easily pulls away from the meat. If you have a good thermometer it's done at around 192. If nothing else, push a fork into the meat and twist, if the meat easily breaks apart and there is little resistance, it's done. Patience is the key and I promise you won't over cook a pork shoulder.