Err on the safe side and figure 2 hours per pound....I used to figure 1.5 and found myself always pressed for time as I like to eat at 6. If you hit a stall that way you will be ok. If done sooner you can always foil, wrap in a towel and hold in a cooler or something. Like yesterday, I did a slab of ribs and put them in at 11 wanting to eat at 6 and they were just right. I usually do the 3-2-1 or straight 6 for a change but the slab was meaty and that extra hour made a difference. Just my opinion, of course, but if this is your first smoke with a chunk of meat allow yourself extra time. Oh, and 225 is a good target temp but be prepared for a little plus or minus there depending on your unit.Everyone wish me luck!! I'm going to attempt my first smoking experience this weekend with a shoulder. Low and Slow. Probably going to do a 6lb shoulder, so I'm thinking 8-9 hours at 225?