I hope this will help.
I just talked to NY, who said the following:
Once a decision is in final form (all the T's crossed), the Paris office meets in plenary session to give its final blessing to panel decisions.
These meetings are held on Friday. However, the party did not know whether it was the lst, 2nd Friday, etc., and said we should call Paris to get the exact information.
Bottom line: Friday appears to be the day, but only once a month, rather than 4 times.