I think Randy was saying that the rhythmic emphasis is on 2 and
4...the chords do usually change on the 1st or 3rd beats of the
measure. Its very common in jazz to play a line that resolves to a
strong chord tone on 1 or 3....right when the chord change
happens.
The suggestion that Randy gave to play the 3rd and 7th of each
chord is a very good one...those are called "guide tones", and
they define the characteristic sound of a chord. If you
experiment with connecting the closest guide tones of each
chord together in a progression, you will have the basic
harmonic framework of the harmony, which is a great jumping
off point for comping and constructing lines:
Try that line over Dm7 / G7 / Cmaj7, where each chord gets two
beats.
keep pickin,
Rob