The one or 2 songs could easily be 6 to 12, but you are talking about people who know nothing of music and I have no idea how much time they will spend practicing.This is on top of the method book and the classical stuff and so on.Learning chords is a very long process. You have to learn each one with all the inversions and be able to play one every other second and then learn to mix them between the two hands. Majors, minors, 7ths aug, dim....you name them.I stress chords cause you say they want to play pop and once they learn their scales and chords, they can pick up any and I mean any pop song and learn it in 15 minutes. This is in basic form of course.
Popular music is jazz-based. It is much less complicated than classical styles.
I asked this is because few of my friends had taken only several mths to a year music lesson at some music school for pop music and they told me that they only played around with chords on their left hand.