The Light On/Off slider allows you to choose the default timing for turning your bulbs on and off. At 0 seconds, displayed as "Instant," the lights will turn on and off instantaneously. If you set a longer time, the bulbs will seamlessly fade their levels up or down over the specified duration. The slider allows you to choose times in 0.25 second intervals.
The Settings menu displays a range from 0 seconds to 5 seconds, but to extend the time even more, simply click on the blue "5 secs" in the upper right corner above the slider. Here you can set a custom duration of anything up to 59 minutes and 59.95 seconds, precise to the nearest 5/100ths of a second.