Pork butt/shoulder is a very forgiving meat.
Time/temp will vary greatly...
If you are cooking at 225 - factor nearly 18 hours (give or take)
Cooking hot and fast over 300 - will be around 7-8 hours roughly.
Myself:- 275 will be around 12 -13 hours later... add a few hours resting end up seeing an 18 hour window.
Your mileage may vary...
Cooking at Mason-Dixon BBQ Services
Lang 84 Deluxe Kitchen known as "The Glamazon" , Custom Klose Backyard Chef... of Snot, and a 22.5 WSM
Lang 60 Mobile - The Damsel II, Lang 48 Patio - The Damsel, Bubba Keg Grill - RIP, Double Barrel Smoker and a BSKD