Anyway, I'm sure many of you already know this but...
So all of the original dances from which salsa sprang were danced 2,3,4 6,7,8. (or in the case of chachacha 2,3 chachacha 6,7 chachacha).
.
The origin of Cha, is Son Guajira, danced on "1" and first used as a Triple Mambo, in a social context , and Cha, is not even considered a latin dance by many DJs and latinos.. and its CHA Cha.... ( 4 and...the Conga slap ).
The 4 and 1,( cha, cha , cha thing ), came out of teaching, and is reputed to be a verbilisation of the noise the feet made by singers in bands, when moving back and forth..