That would work. Plus you can reuse it for other various items, such as marking how catv/telco/ethernet runs, hvac, plumbing, electric, for your record, if any changes are made.
Just put the words "Water, Gas, Electric" in the places that the shut offs are. Also helps for anyone that may be house-sitting for you also, so they know that it is on the electric panel. Just place a clear sheet protector on the outside of the breaker panel, and slip this sheet in there, with the numbers for utility emergency numbers, a couple of plumbers, hvac, electrician in order of who first to try, then so on.
I tend to shop around for hvac companies every couple of years, but have a good roofer that does some other stuff for me structurally if I need, along with his father, and a guy that does a/c & my plumbing. Anything else I play Russian roulette when needed.
__________________ Ren: Now listen, Cadet. I've got a job for you. See this button? Ren: Don't touch it! It's the History Eraser button, you fool! Stimpy: So what'll happen? Ren: That's just it. We don't know. Maybe something bad, maybe something good. I guess we'll never know, 'cause you're going to guard it. You won't touch it, will you?