Usually pork shoulder takes between 1.25 and 1.5 hours per pound. You can figure that at about half the total cook time you have gotten as much smoke in as you are going to get. So for a 10 pound shoulder you can cut the smoke off around 6 hours in (total of 12-15 hours) and you are likely fine.
At that point you are just looking to keep a steady 225-250F until you hit your target temperature. I like about 195F internal for pulling. Once I hit that I rest it about an hour then start the pulling process.
"First you start with a pound of bologna..."
-My Grandmother on how to make ham salad.