Your breast is already brined.
When I do an 8 or 9 pound bone in breast, I smoke for about three hours with apple. For total cook time to a temp of 170, I plan for about 5 1/2 hours. Since your breasts are smaller, you shouldn't need as long. I'm guessing about four hours.
Preheat your smoker for about half an hour before adding the turkey.
Let the turkey warm up on the counter for a half hour or so (the breasts are on the smaller side, so less time) before placing in the smoker.
A foil wrapped brick tucked under your puck burner acts as a heat sink, improving your heat recovery when you add the meat. If you do this, increase your preheat time to closer to an hour.
Open your vent to at least 3/4 open. Poultry, especially brined poultry, contains a lot of moisture. You need the vent open to let the moisture escape. After an unfortunate incident, I removed the vent damper from my smoker in order to prevent future mistakes.