Go by internal temp not minutes per pound. Turkey likes higher temps in a smoker, say 275F+. I typically do mine in the 325-350F range and the time can vary. I like to smoke poultry with a 50-50 mix of Hickory and Cherry.
Last Thanksgiving I did two 18.3 lb turkeys, a Nob Hill All Natural Turkey on 11/23 and a Dietsel All Natural turkey on 11/26. With the Dietsel I loaded up the lower tray with a big roaster full of veggies. The smoker was able to maintain 325F with the Nob Hill and the thigh reached 165F in 3hrs 15 minutes. With the Dietsel and the veggies, that's a huge heat sink, so the smoker poked along at 280F. The thigh reached 165F in 4 hrs 30 minutes.
I did not brine or inject either bird, which I usually do. The Dietsel was the more flavorful of the two and delivered noticeably more meat than the Nob Hill bird. I put nothing but rub on the skin of the Nob HIll bird and it came out with a nice color. I put butter on the skin of the Dietsel and it came out kind of black. Tasted great, just not a nice color. Pics are below.
I've still got one in the freezer. Probably time to thaw, brine, and smoke it.