At a range of 250-275°F, you can figure 1.5 hours per pound on a Butt. I would add 2 hours to CYA 'cause stuff happens! So 14 hours, give or take...When the IT is around 205°F, the bone is loose and a probe slides in with no resistance, the meat is done. You only need a 30 minute rest on the counter, tented with foil, to cool until able to handle. OR if the meat is done early, double wrap in foil and towels, place in a cooler and it will hold hot about 5 hours longer...JJ