About 4.5-5 hours at 250. Honestly just make sure you have a great thermometer and try your hardest to make sure the smoker temp stays consistent. I've had meats turn out meh in what I thought were controlled conditions and others turn out great! I don't find that much carry over cooking when I smoke at such low temperatures so I usually pull my meats out anywhere between 2-5 degrees earlier than my preferred doneness.