To turn on the On/Off Timer on your TV, you must first set the clock. If you do not set the clock, the On/Off Timer will either be inaccessible and grayed-out, or accessible, but you will not be able to set it or turn it on.

If you have not set the clock click on "Setting Your TV's Clock Below"

If you have set the clock click on "Setting Your TV's On/Off Timer Below."