The only other bit of info to add is that when you have more pins than you want switching events, put the spare pins where they won't switch. Eg put them in the off ring after it's already switched off by a previous pin.
FWIW I think these are the best of the various timer types. All types have their compromises, with these it's half hourly switching at closest & risk of losing pins. And finite number of pins. You can of course use them as rundown timers too.
I assume someone mentioned you turn the dial to set the time. It only goes one way.