We base our rates based on the time we start and end any event. If we start the ceremony and then stop playing since there are live musicians, we cannot technically be on "break," since we're there at the event and cannot leave.
Even though we may not be playing music, our DJs will often still make necessary announcements, call tables, facilitate toasts, speeches, etc. So we will charge based on the total amount of time we're there, from the time we start until the time we end (we don't charge for setup/breakdown time).