Somebody somewhere suggested that 12 of full lighting is too much. While the day in the tropics may last 12 hrs, it is not at its strongest that whole time. It really only blazes for 3-4hrs. So if possible you might want to start off with something weaker, then turn on the main light, and then back to something weaker. What time of day you do this is entirely up to you. Because I leave the house very early in the morning and want to feed my fish before I leave I program to have the lights on at 6am and they're off at 11am. I don't have supplemental light just yet, but regular daylight from the window is enough to keep the fish awake and swimming. They tend to go to sleep between 5 to 7 pm! Some people run their tanks on a night-schedule altogether!
PS: Electricity is cheaper at night, too!