21:20 Jun 9, 2011 

I don't suppose it could possibly have anything to do with a song of that name from 1976 by Michel Delpech?? (not that I have ever heard of it myself...) See http://musique.ados.fr/Michel-Delpech/Ce-Lundi-La-t131357.ht... and ttp://www.youtube.com/watch?v=1iM7NZ49GOA

15:56 Jun 9, 2011 

"that particular Monday" or, if somewhere else in the text the relevance of it being Monday comes to light, together with the time of day, "that Monday morning (or afternoon, or evening)". If the relevance of it being a Monday does not come up elsewhere, you could take the risk of eliminating Monday and just saying "that day/morning/afternoon/evening" ... the risk being that when volume 2 of the quadrilogy comes out, the relevance of it being a Monday will be revealed.