At the End of the Day...

http://www.boundlessline.org/2009/07/at-the-end-of-the-day.html
Coinciding with the cessation of the sun's light rays directly impacting our part of the earth......no?

How about "When the lion lays down with the lamb...." Or "When the streaker finally jettisons his last shred of dignity and steps onto the field..." or even "when the tea kettle whistles....."