How do I set the timer on the Homedics CMTF91?

Press the timer button until the desired auto-shutoff setting is displayed. The timer cycles through 4 hours, 8 hours, 12 hours, and 0 hours. To cancel the timer at any time, press the timer button until 0 hours is displayed, and always ensure the humidifier has a full tank of water before using the timer setting. (Page 7)