You may choose any day of the week to start your week by editing the settings in the calendar app:

  • Go to calendars.
  • Click on the little cog wheel in the lower left next to + New Event.
  • Select the desired weekday as start of the week.
  • Click Save.
  • The calendar will be reloaded and displayed with your new settings.
Additionally you can set the time format to suit your local standard.

You may read more about this feature here: http://blog.fruux.com/2014/12/22/calendar-settings/.