How do I use the timer function on the Graco Slim Fit?

The timer button, located between the two speed buttons, sets the swing time in ten-minute increments up to 40 minutes. Push the button once for ten minutes, and push again to add more time. The active speed light will blink once for every ten minutes programmed, and the number of blinks decreases to indicate remaining time. Both the swing and music will stop when the timer runs out. To cancel timer mode, press and hold the timer button until the light stops blinking. (Pages 31-33)