What is an appropriate progression of music literacy curriculum for a child through high school?

In my work with non-profits working in music ed, I have come to recognize that music literacy, like all things, takes root best when presented as early as possible in a manner that incorporates ear-eye coordination with creative projects.  Dalcroze, Suzuki, Kodaly (again, I'm not an expert) all lean toward the incorporation of musical ideas through the ears, returned with the body and voice, before the introduction of the written symbol.

It would follow, therefore, that steps would need to be taken to introduce these concepts using the existing early childhood framework in place.  I'm also saying this as it becomes obvious that programs are suffering from under enrollment, which could hopefully be stemmed by (more attention paid to them, but specifically)  1) upgrades to existing programming that will retain already enrolled students, 2) New programming meant to draw in new populations and 3) a progression of curriculum to shepherd students through their studies and sustain multi-year enrollment.  The last one is also coupled with the establishment of a community atmosphere, thereby making the school not just a drive-thru for lessons, but a place where kids can come to make music together.

Back to the initial question, if we fall in line with what has been established, in that the aural and kinesthetic experience of music should be fostered before the advent of the visual into the learning scheme, when should honest-to-God Eurythmics and solfege start as a path to music literacy?  I come up with a bit of resistance on this, to tell you the truth - not from myself, but from colleagues (and I can't figure out why).  I have taught semesters of straight-up solfege classes to 5 year olds and they love it (and it's hilariously fun).  Many studies have shown that young kids need only be present to absorb, so why present it as early as possible? 

It presents a marketing issue, however.  In the overabundance of 1) "Mommy and Me" programs and 2) Young parents who will do anything to try to give their kids a leg up, how do you differentiate your programming and get the points of educational benefit across?  That's question three.