Some timers, like this one to your left, have the electrical  wiring close to the switch. BE CAREFUL there is HIGH VOLTAGE behind that plastic insulator!

Did you notice the insulator is cracked?
Did you notice there is NO Ground?
This timer is on an old home that didn't have ground wiring installed originally. Watch out that you don't become the ground handling this timer!

Setting This Timer

To adjust these timers, pull the yellow dial towards you, then turn it until the silver pointer is at the correct time. This timer is showing 10:00 AM.
When the pointer is at the correct time, gently push the dial in, until you feel it seat into the gears. DO NOT try to set the dial while the pointer is over the on/off trippers.