Welcome to the forum.
However....
I highly recommend not doing a turkey for a SPECIAL day for the first time on a brand new smoker. Too many things in the learning curve, most of it has to be practical experience.
We'll help where we can, but that'a a lot of pressure for you, the new smoker and the first time turkey.
You need to validate that the smoker temp is right it (it usually is)
You need to test the probe (for accuracy)
Not trying to worry you, but my #1 recommendation every year is don't wait for Thursday to do a dry run the first time that day. We've seen the challenges.
But then again you'll come out just fine and nothing to worry about.
Biggest issue is timing for first time users.
Here are some times from another post I made, there is a lot of variance:
235 for 6 hours (8# breast) (45 min per #)
230 for 2 ¾ hours (13#) (12.3 min per #)
225-250 for 6 hours (12#) (30 min per #)
225-250 for 3.5 to 4 hours (10# bird and 6# breast) (24 min and 40 min per #)
225-275 for 3 ½ to 4 hours (no weight listed)
225 for 8-10 hrs (was partially frozen on purpose) (no weight listed)
225 for 4 hours and 350 for 1 ½ hours (21#) (15.7 min per #)
From 12.3 to 40 min per #