The Whish has two timer options, 6 hours or 8 hours. Timer 1 is 6 hours and Timer 2 is 8 hours. To set the timer, turn on the Whish, select (by a button on top of the device) the 1 or 2 option, and the timer will begin. If you want to disengage the timer, simply unplug the Whish from the wall outlet and plug back in. (Note: This will default the sound setting to Fan 1.)
You can also choose to not use the timer feature and run the Whish continuously until it is turned off.