If you haven’t read Part I, have a look there first.
At some point, the graphic notation will start to prove difficult. Students who are making more conscious, precise decisions about dynamics, pitch, and rhythm will need an equally precise system for notating their sounds. “Prep” the transition early on, and often, by exposing them to traditional notation and pointing out what you can see (familiar rhythms, pitch relationships, clefs, etc.). This way the symbols are already familiar and it just becomes a matter of taking it to the next level.
Students can begin by using the notation that they DO know. For example, they might write quarter notes and eighth notes higher and lower across a graphic score before they understand fixed pitch notation. As they gain literacy in traditional Western notation, they can incorporate more and more elements into their graphic scores.
As a final note, decide what your priorities are. Over the years, I have spent less and less time on explicitly teaching traditional Western notation. Students who need it are learning it in their private lessons. Many of the other students find it tedious and discouraging when they should be learning to understand the purpose of music, to enjoy listening to and making music, and to interpret music within its context. I present my students with many kinds of notation, and I expose them to traditional Western notation whenever it’s appropriate. And don’t get me wrong, I still ask students to try to notate compositions now and then; it is a skill that I want to develop in y students. But I am no longer pulling my hair out trying to get every single child to document their creativity in this specific way, I am no longer drilling students on lines and spaces, and I have a happier, more creative classroom because of it.