Jerry, most importantly, don't rush the brisket, you must have lots of patience with this cut of meat. Most just can't wait to pull it, slice it and enjoy it, then moments later after they just couldn't wait any longer, they slice into a tough piece of meat only to be disappointed. As oldschool mentions, yes, wrap it around 160 to 165 degrees IT, then continue to monitor until the IT is in the 185 range, at this time begin to check for tenderness with a toothpick. Continue to do this until the toothpick slides in easily, like a knife into butter, or with little to no resistance. The finishing IT will be anywhere between 185 and possibly 210 degrees, it really depends on the brisket itself and your cooking temperature. If cooking hot and fast, 275 and up, you will finish at a higher IT say 205 and up, if you are cooking slower and lower 225 and below, then you could finish in the 185 to 195 range.
Add 1 cup or so of beef broth or your favorite dark beer to the foil when you wrap, I prefer to use foil pans also over the alum sheets, much less chance you will lose those precious juices from the cook. These juices can be poured back over the sliced and chopped meat to turn a dry brisket into a good one and a good brisket into a spectacular one.
Also, if you find yourself in a time crunch, once you wrap the brisket, you can always throw it in a 300 degree oven to finish. You will have no side effects from this method, plus you will have it ready on time more than likely. Don't forget the all important rest period, this is probably the second most important part of a brisket cook for a couple reasons. First of all it gives the meat a chance to relax from the hours of stress you put on it during the cooking phase, possibly reabsorbing some of the juices, but you also need the meat to have dropped to at least 170 degrees IT during the rest or you'll end up with a juicy cutting board not a juicy brisket. As the meat relaxes, the juices will redistribute to the center away from the outer edge where it is forced to during the cook.
Most of all have fun and patience! Good luck!