Till it's done!
Sorry, I had to. Cook it until it reaches 195* or 200* internal in the flat. I would wrap with foil at around 160* and cook in the foil until it hits your final temp. Separate the flat from the point. Wrap the flat in foil and a a towel and put it into a cooler for an hour at least. While that is resting cube up the point, toss with sauce, and put into a pan and back onto the smoker until the flat is done resting. There's your burnt ends. A 16 pounder will take a pretty long time. At 225*- 250* pit temp it'll probably take over 12 hours for sure.
It always seems different for everyone and every brisket cooks differently. Good luck!
