I have two blue actinics turn on around 4PM, then the remaining four lamps turn on around 7PM and are off around 3AM. I do this because the tank is in our main room, which is all glass to the west and it can get really warm!! I keep the shades closed when its forecast to be warm for the day to keep the house cool. When the actinics turn on, a fan turns on as well.
It may seem silly to turn the lights on during these hours but I have no other means of keeping the tank cool. Also, I have no time to look at the tank during the day-- it's nice to have the lights on when I get home!