Glad you asked. I generally believe in knowing what is "important" to learn and what is not. I see only a very small amount of music theory as being necessary to the early stages of learning banjo. Otherwise I see it as sort of (temporarily) wasted effort when there are much more important things to master, and a possible source of needless discouragement if a person does not easily absorb music theory-type material.
For the fundamentals of playing, and what I consider the appropriate steps, see my Bluegrass Songbook, Bluegrass Jamming video, and Beginning Bluegrass Banjo video. I feel these (and my Bluegrass Banjo book) state well what I think is efficient and fun learning. This would include "chords and how they fit in", which is about all the music theory you need to know for now.
These instruction materials can be ordered from the Store section of my web site.