One thing you are gonna need for sure, are a couple of good meat thermometers. TIme is a good baseline to plan your smoke, but only internal meat temp dictates when it is done, especially for a newbie. IMO plan your smoke so the brisketts are done a few hours before you want to serve them, this is for two main reasons: 1) the meat is done and you and your guest are not waiting on it (possibly for hours) and 2) it lets the meat rest and helps to redistribute the juices in the meat. Just make sure if you finish it early, wrap it in foil if you have not already done so, and then wrap it in towels and place in a cooler, they will hold for several hours in a cooler.
Are you just doing flats or full packers. IMO I would suggest doing flats, I am pretty sure you are gonna have PLENTY of meat for 14 people.
Yes it is a pretty good undertaking for a first smoke, not to mention you also have a new smoker to figure out too.
Good luck and don't forget the Q view.