I would push for a setting of first day of the week, in the International module in Preferences, as there is no such feature today. Why? Today, the first day of the week varies around the world, in some parts of the wold, mainly in the US, Canada, Asia and Australia, it is Sunday. In Europe, except Portugal it is Monday. I the Middle East/West Asia and North Afrika it is Saturday. Some places even have Friday. The first day of the week sets the layout of the calendar, and the Calendar will look a bit different, depending on this day. This wouls also require the Calendar in PC/Geos to woek this way. So a setting of Friday, Saturday, Sunday and Monday for the first day in the week would be good. Here is a link to a map of the first day of the week: https://en.wikipedia.org/wiki/File:First_Day_of_Week_World_Map.svg
Weekday setting in International/Preferences
At least, adjust the Calendar to the international standard ISO 8601, in that standard, monday is the first day of the week.
Hans