As accurate as a Swiss designed timepiece, and although arranged in 8 voices, ‘W’ is actually a four-part round with a ‘tic-toc’ accompaniment. Keep these, literally, as precise as clockwork with appropriate ticking gestures if you so wish. Once the upper and lower voices have sung the round against the ticking chords, the full four part round then runs it course before winding down.
A very dear singer friend runs two choirs ‘TIC’ (The Improvising Choir) and ‘TOC’ (The Open Choir). Not directly relevant but I just thought you should know!