For me, it's important to include musicality and expression, particularly that of phrase shape, from the very beginning of the learning/rehearsal process. The problem with ignoring the shaping of phrases (dynamic, agogic, stressed and unstressed syllables, etc.) is that the choir learns an unmusical shaping of the phrase which then has to be un-learned (and that can take much longer than learning it correctly to begin with).
Of course, we all isolate elements (pitches, rhythms, text, intonation, etc.) in rehearsal, and sometimes the writing is too difficult for our groups to do without some drill. But . . . while drilling pitches or rhythms (let's say text on rhythm only), one can still begin the process of shaping the phrases. Robert Shaw style countsinging can also have phrase shapes built in--this technique doesn't mean to sing without shape or sense of where each phrase is going (make sure you come to Pamela Elrod Huffman's session at ACDA in Dallas, where she'll focus on Shaw's rehearsal techniques).
Ultimately this is much more efficient and the choir will begin to sing music, not just notes, from day one.
The other part of this is that your singers become involved with the music more. Since I work on musicality and expression all the time, sometimes it only takes a reminder from me ("sing more musically") and the choir will know what to do. It's important to teach the whys and hows of this as well (part of teaching them to be better, more expressive musicians). What are the clues to musical phrasing? They need to listen for harmonic dissonance and release, think about text stress, become aware of the important words in a phrase, to be aware of musical contour (the rise and fall of the musical line). They need to know what the overall shape of a phrase is (where does it begin and end? we can sometimes disagree about that!) and how to determine the "goal" of each phrase (where is it going? what's the most important syllable or beat towards which one phrases?). . . and especially to remember that all notes are not equal in a phrase!
Some elements of expression may have to wait, but don't wait too long!
And finally, some of my favorite quotes about phrasing:
Harpsichordist and Pianist Ralph Kirkpatrick: "The essential expressive quality of a melodic interval lies not in the notes themselves, but in the space between the notes, in the manner in which one gets from one note to another."
Conductor Robert Fountain: "Not just the desire, but the passion to keep the line going."
Composer Virgil Thompson: "Is this music just a piece of clockwork, or does it also tell time? . . . have I been moved or merely impressed?"