Related Questions:
Change my calendar to Monday-Sunday
Change my Calendar Saturday-Friday
Change my Calendar to Sunday-Monday
How do I change the day my Calendar week starts?
Procedure:
These steps can only be taken by an Administrator. If you do not see these options, please consult an account admin.
Select Settings on the left-hand sidebar
Select the Organization dropdown
Click on Organization Settings
Click on the Other Settings tab
Scroll down to Start Week On
Select the day you would like your week to start
Click Save