LOL Mrs Duck!
ceman, you're doing great, but how much do you want them to read and why? I have a pretty carefully planned "scope and sequence" from grades one-five (ages 6-10) but do very little music reading with the 6 year olds. I want them to hear the steady beat (also called the pulse), understand about simple rhythm patterns and be able to hear them in a song, especially patterns that are relevant to the song ("cat goes fiddle-I-fee" for ex.). Above all, I want them to enjoy music and to feel that they can sing and play along (with drums, tambourines, wood block, etc.)
By the end of grade 5 they should be able to read the syllables and line-and-space names of the treble clef, read a few time signatures, hear major and minor keys, keep a steady beat, read and play several complex rhythms while others are being played at the same time, sing in 2-part harmony, and so on. In the early years I build skills that lead to this confident musicianship. So at age 6 they do "pre-reading" (pictures: cat cat fiddle&bow cat cat)
Later I would add the symbols and even later use the symbols with no pictures. My goal for the end of the school year is that the kids age 6 to recognize ta, titi and rest and play and sing them. It's a whole school year of re-enforcing those and other melodic concepts (do re mi sol la). A whole year! So still think about how much you want them to know and what sort of music they will be doing as they continue to learn and grow. It's great that you're spending the time with them!