Salsa is a non-standardized dance. It has a complicated rhythm and people hear it the same but feel it differently. That is why each instructor seems to put their own twist on how it should be danced. Some believe you should break on "one", others say break on "two", and still others break on "three".
The only thing about Salsa that has a consensus is the timing. Each measure of music has 4 beats (4/4 time) and an 8 beat (two measure) phrase (1 & 2 & 3 & 4 &;5 & 6 & 7 & 8 &). It has "Clave Rhythms" and a "Quick, Quick, Slow" dance rhythm. Beyond this everyone seems to have different opinions.
The word "Clave" has two meanings:
1) The "Clave Instrument" is a pair of polished resonant wood strikers.
2) The "Clave Rhythm" is a five-note syncopated rhythm across two measures of music which serves as the foundation for all of the rhythmic styles in Salsa music. The most common variation is the 3/2 (Son Clave); 3 beats in the first measure and 2 beats in the second measure. The two measures together comprise a phrase. It has a "strong" measure containing three notes and a "weak" measure containing two notes, resulting in phrases beginning with either measure, creating "3/2" and "2/3." phrases. Listen for this rhythm when you dance, and try and feel the distinctive 2nd beat, called the bomba (barrel drum). The rest of the music is built round the "Clave Rhythm" by adding complex conga, timbale, brass, guiro, bell and bongo rhythms.
Many Salsa dancers have problems hearing the beats - in particular to identify the first beat in the 8 beat phrase. This is because the Salsa rhythm is created by a complex blend of different rhythm instruments. The congas (drums) usually dominate and can occur on any beat (or even in between beats) while the cowbell occurs on beats 1, 3, 5, 7. The "Clave Instrument" sound occurs on 1, 2&, 4&, 6 ,7 (3/2")- if they are present at all.
Some people dance the cowbell others the "Clave Instrument", some break on "1" some on "2" and others on "3". The L.A. Style Salsa rhythm is Quick, Quick, Slow; Quick, Quick, Slow, using the 1,2,3 and 5,6,7 beats. The trick is to be able to hear the difference between the "Clave Rhythm" and the constant 1-2-3, 5-6-7 beat.
This all sounds very complicated and you can debate forever what is best. The best is what feels good to you. When dancing Salsa socially, does it really matter what beat you start on? Dance whatever you are feeling in the music and just let it go!!!