Mike Harvey writes:

Carte Orange quick facts
...
* The weekly pass (called a coupon hebdomadaire) is valid Monday to
Sunday only. Be sure you can communicate the dates that you want, or
that you'd like a Carte Orange for the next week starting Monday.
Otherwise you may be sold a pass that is only valid for the rest of the
week.

And then:

You can buy it up to Wednesday for use in the current week, and from
Friday for use the next week. (No weekly passes sold on Thursdays)

Make up your mind!
--
Mark Brader | "I'm surprised there aren't laws about this in the USA..."
| "Of course there are laws about this in the USA.
Toronto | Without even reading further to find out what 'this' is."
| --Rob Bannister and Evan Kirshenbaum