This timer is one of the best timers in existence , and the reason is that it has been tested for many years and it’s made to last , something that is not very common this days , it’s 100% mechanical/electric and still made with a metal body. There are other more modern ones that are electronic and made with plastic , and more expensive than this ones. But so fragile that if you drop them they will probably break.
To put the timer on time you pull the yellow disk towards you and turn it until the fixed middle arrow is pointing to the correct time of day,then you pull back the yellow disk again to it’s position. To set the ON/OFF switch you unscrew the small screws on the metal objects on the side of the yellow circle to move them as needed pointing them to the hour when you want to turn on the sign and turn off .
You have to tighten the screws with pliers because if you just tighten them with your hand they will move a soon as the hit the switch , so they have to be tighten with pliers .
There is a manual on /off switch that will help you overide the timer so you can turn the sign on and off as needed