This is lengthy but maybe there will be something in here useful....
Well, last weekend I did my first smoke, two pork butts, in my new 18.5" WSM. I trimmed the butts, tied and applied dry rub; in fridge by 8 a.m. since I was doing an overnight smoke and wanted at least 12 hours in rub. 8 p.m. I pulled butts from fridge, sprinkled a bit more rub on, let sit on counter while I got WSM ready.
I filled ring with briquettes, used Guava wood chunks for the smoke, and added 3/4 chimney full of lit coals to the top of that. (full enough so the water pan was almost sitting in the coals). Put the middle on the WSM, foiled water pan in and filled, put butts on racks and put in smoker.
Lid temp hit 250 quick, top vent open 100% I closed up bottom vents to about 25% open. 1.5 hrs. later I closed bottom vents to 20% open. Lid temp was 250 at midnight, and when I checked again at 5 a.m. At 6:30 a.m. lid temp was 225 so I stirred coals, temp spiked to 260, then settled back to 250 in less than an hour.
Pulled both butts off at internal temp of 190; the 7 lb'er done at 8:30 a.m. (11 hr 20 min., the 8 lb'er done at 10:00 a.m (almost 13 hrs). Foiled the butts, let sit on counter under towels for about an hour each, then pulled. They were pretty close to perfect
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Have fun !