The coach has little to do with this situation.
The problem is with the shooter.
Everybody else lined up, one oral warning to the shooter (loud enough for the coach to hear) to get to the line (if I'm in a good mood).
Everybody else lined up, and no movement by shooter toward the line, with no timeout involved, technical foul.
Timeout involved, everybody else lined up, and no movement by shooter toward the line, place the ball on the line, and go from there (another timeout, or a violation).
Won't happen again.
I promise.