One, two, three, go!
Thank you. And for the phrase, like starting for a race, One, two, three, go! ?
4 Answers
En México se dice: "¡Uno ... dos ... y, tres!"
Sam the sham puts a little 'Spanglish' in it, but his accent's pretty good though.
I've read somewhere, in a kiddy story, I think, that it is 'a la tres... a la dos... a la uno... ya!" (you count down for races, don't you?). You can probably reverse that to 'a la uno, a la dos, a la tres!" for miscellaneous purposes (the 'ya' seems to be like 'go'. You don't usually use that in normal counts).
"Uno... dos... tres... ya!" seems like a sensible translation as provided by Google. You will definitely be understood, at least.
Someone might have a better idea, so you should wait and see.
Preparados.. listos....¡ YA!
o ¡Al jugar!, depending on the sport.