Skipystu
4 hours for the smoke. Cook time would depend on several factors. Could be up around 18 to 20 hours. Also, do you want to slice it or pull it?
Typically you don't go by time, you go by internal temp say around 180 deg F. You can use the FTC (Foil, Towel, Cooler) to hold a good meat temp for many hours so plan on finishing early and holding the temp for the time you need.