Looks like a great plan, Eric! My only worry is the amount of time in the smoker...I would go with 2 hrs/lb to be sure that you can get it on the table at 7pm and allow at least 1 hour of rest. So for a 7lb butt, I would allow for 14 hours in the smoker, plus one hour for rest, or a total of 15 hours. You may not need the full 2 hours, but if you do, you will miss your 7pm target. So, I would get it on sooner than 6am. Now here's the downside...if it only takes 1.5 hrs/lb instead of 2, then the butt will reach your desired IT before you get back home at 5:30pm for a 7lb butt, but you will definitely make it for dinner at 7pm.
It's just very hard to anticipate the actual time needed -- but here's another suggestion: start at 6am, and check the temp when you get home at 5:30. If the butt has not reached your desired IT, you could move it to the oven and finish at 350F or so. This would get you to the desired temp quicker and allow sufficient rest before serving at 7pm. Just another thought.