I echo the advice from Walt and Gregg. With time constraints, always allow the extra time...2 hours per pound should work nicely, allowing 20 hours total. The last butt I did at 235F finished easily under the 2 hour limit, and you can always lower the temp to 140 for a warm and hold if needed. Always better safe than sorry on the variability of smoking butts!
I also brine every time. I have a 2 gallon (I think) Rubbermaid container that holds a butt nice...this past weekend, I used it to brine two 5# turkey breasts and they fit perfectly in the container.