Hi,
Thanks for using the Events Calendar.
Here on the pre-sales forum, I’m afraid we do not provide technical support. I would ask that you take any technical support questions across to our wordpress.org forum – our staff scan it periodically and other community members may also be able to help out.
The Events Calendar
Having said that this is a WordPress setting.
To change the start day for the events calendar go to this setting in your admin and choose the day you would like:
Admin > Settings > Week Starts On
Thanks again!