One musical motif that relates to the time of day and changes through the course of Spenser's Epithalamion is the singing that occurs above and leading into the 17 variations of the refrain:
The woods shall to me answer and my echo ring.
The refrain at the end of each of the 23 full stanzas [the 24th is an envoy: A short closing stanza in certain verse forms, ... summarizing its main ideas (Dictionary.com)] is introduced by a progression of who sings to whom and for what purpose. The singing reflects the movement of the poem from the groom's solitary musing before the break of day through to the height of the wedding festivities, which stretch from bright day into dark of night, to the welcome solitude of the new-wed couple alone in the cover of darkest night that returns them to where the groom began before break of day.
In stanza one and before dawn, the groom (the poetic speaker and groom is Spenser himself) beseeches "Ye learned sister," his Muses, to adorn their hair in garlands of flowers and help him sing the praises of his beloved:
And having all your heads with girland crownd,
Helpe me mine owne loves prayses to resound;
So Orpheus did for his owne bride:
So I unto my selfe alone will sing;
His song, sung alone, will ring in echo as the woods answer with their own song. As John B. Lord details, the groom's early morning starlit solitude changes in stages as he bids the sun arise then awaken his love and "to her of joy and solace sing." Then he bids the nymphs to "deck the bridale bowers" of morning and "this song unto her sing."
As the stanzas progress, with the woods answering each who sing while the day grows lighter, so does the singing progress and change. For example, after daybreak, when he bids his love awake, he seeks that she may "hearken to the birds love-learned song." After finally sending his guests home at late night, he bids the dark of deep night to be a cover to his union with his fair love while silence replaces the song of joy sung during the day:
Conceald through covert night.
Ye sonnes of Venus, play your sports at will:
For it will soone be day:
Now none doth hinder you, that say or sing,
The groom finally bids all to be still at the early hours before daybreak, returning to the hour at which he began his song:
So let us rest, sweet love, in hope of this,
And cease till then our tymely joyes to sing:
The woods no more us answer, nor our eccho ring.