Set first day of week in iOS

I have Monday set as the first day of the week in my iPad Calendar settings. I can find no such setting in OmniFu. When I tap to pop up a calendar for setting Due or Defer dates, the weeks start on Sunday.

Is there any way to change this?

Interested in this as well. Would like Monday to be the start of the week.

The Region (country) setting in iOS determines the first day of the week and this is applied by all internationalised apps. The iOS Calendar app and some 3rd-party calendar apps have an app-specific setting to choose a different first day of the week, but not OmniFocus. You could send an email to Omni support to suggest this feature.