I leave the basking light and UVB light on together for 10-12 hours a day. A light (even a colored "night" bulb) should never be on at night as this will disrupt the beardie's sleep--a ceramic heat emitter should be used instead of a basking bulb at night if your home falls below 68 degrees.
I use an outlet timer to control the lights as described in the previous post. It's much easier to automate that part of the process. Basking and UVB can be on the same timer.