I always buy the biggest briskets I can get usually from 12 -16 lbs. I buy them early, trim the fat cap down to 1/4 inch or less and season lightly with salt pepper and garlic and then wrap it in plastic wrap for 1 to 2 days. With 8 people there will not be tons of left overs and left overs are a good thing.
I cook mine in a full size stainless restaurant pan and take it off when it is probe tender. I start probing around 195* and probe every 30 minutes until it is done. This is usually 7-8 1/2 hours cooking between 250 - 275. I typically take it off wrap the pan and throw it in the freezer until the brisket is cold enough to slice easily. I then cut the point from the flat and I usually slice both on a electric slicer and lay the slices back into the restaurant pan where they came from. I usually slice about 1/4 inch thick or a little less. Sometimes I will cube the point for burnt ends.
I usually cook this a day early so I can rest up for the party, but I also do it on the same day. When I am going to serve the brisket I pour a can of beef broth over the brisket still in the restaurant pan with the limited fat it cooked in, double wrap the pan in heavy duty tin foil and put it back on the smoker or in the oven. On the smoker I again get it up to 250-275 for an hour, in the oven 350 for 45 minutes. So far every one has devoured the brisket and what ever leftovers are there are fought over. They have all turned out moist and tender with great flavor. A caterer friend taught me the restaurant pan trick, but after 25 or so I am totally sold on it. hope this helps you some.