Primias? ...the workweek starts on Sunday?
In Oz, the "week" lasts five days: Primias (or Primiday), Secundia (Secunday), Tritias (Tritiday), Quadias (Quadday), and Quintias (or Quinday). Quintias is the day most people take off work, but many have staggered schedules. But "Primias" is equivalent to "Monday" for us. BTW a "day" in Oz is 10,000 seconds (divided into 20 "hours") compared with 86,400 for a Terran day. The only time unit exactly the same for Oz as it is for us is the "second," which is an ISO measure.
Five of these weeks in a "cycle" (something close to a month), twelve cycles in a "year" (which is 18 Terran days shorter than a Terran year).
I have all this worked out on a spreadsheet I might publish for my Patreon supporters.