Don't forget to cure that new
WSM before you throw your meat in. Rub the inside down with olive oil or bacon fat and then run your temps up really high to burn off any chemical taste from the factory. Use this time to get used to heat regulation inside the
WSM. Then let it cool down and clean it out before putting "real food" inside. Nothing ruins a good pork butt like burnt paint.
As for the timing of your smoke, I like to allow plenty of extra time, but ultimately when you want to eat (D-Time)will be the determining factor.
D-12 Start the pit and get the pork butt out of fridge where it has been resting overnight all rubbed down.
D-11 Put the pork butt into pit and get the temps back to 225ish.
D-10 Spritz pork butt.
D-9 Spritz pork butt.
D-8 Spritz pork butt and get the Ribs out of the fridge to begin to come to room temp.
D-7 Spritz pork butt and put ribs into smoker.
D-6 Spritz pork butt AND ribs and perhaps wrap pork butt in aluminum foil.
D-5 Spritz ribs.
D-4 Wrap ribs in aluminum foil with apple juice. Add ABTs or Beans now if desired.
D-3 Check internal temp on Pork butt. Should be at 200ish. Remove and place into cooler if so.
D-2 Remove ribs from foil and put back into smoker. Warn the wife that food will start coming inside in 90 minutes and for her to have everything else ready!!
D-1 Check ribs and probably remove them from smoker. Make sure to take paper towels and a knife outside with you so you can "verify they are done".
D-30min Remove pork butt from cooler and put into large pan. Get two large forks and shred it. Add whatever finishing sauce and juices you want at this time.
D TIME MUNCH OUT!!
This should give you a baseline guide of each hour what to think about cooking both. IF you see you are not able to maintain temps properly, you can always finish stuff in the oven.