You've already gotten some good answers. Here's another, based on the music, courtesy of one of our local instructors. You may know that music has "downbeats" and "upbeats." The 1 beat is the downbeat; 2 is an upbeat. Cha-Cha (and other Latin dances) is an upbeat (both in the colloquial and musical sense) dance. And it looks different if you were to "break" on the 1 beat. The instructor I mentioned convinced his audience by dancing a simple (American) Waltz box starting on the 2 beat rather than the 1 beat. It looked completely different.