Commands before shooting? Roll camera, sound...

Lights, Camera, Let's Start Now!!!

Nahhh sorry LOL!

You can say whatever you want.

It's true though. All that matters is that your cast/crew are all on the same page, and it's not that complicated to achieve this. On my tiny-budget films, I usually just want to confirm that both camera and audio are rolling. On rare occasion I might have to call for "quiet on the set", but since my sets are normally just a handful of people, I don't use that phrase because to do so would be kinda dick-ish, when I can just politely address the offending parties by their name.

On my next feature, we'll be shooting a handful of scenes guerrilla, in very public places, with a handheld cell-phone as camera. I don't want people who aren't involved in the production to know that we're shooting a movie so we're going to use code-words to replace "roll-audio", "action" and "cut". It's gonna be sneaky and fun. :D
Actually when I directed a short film I let the DP call out action cause the DP was always the last one to be ready. So I kept telling her, just say action whenever you are ready. So she kept doing it. But maybe this was a mistake and the director should do it, to keep things clear.

But since it was a small set, everyone understood that we were just waiting for her to be ready, and she would call it once she was, and it's just faster than her telling me she is ready, and then I say action after, where as she can just say action instead.