Hi @Valentin,
It looks as though this feature has not yet been implemented as there is currently no way to adjust the week start in the date picker. I’ll mark this as a feature request to put back on the support team’s radar.
Thank you!
In Europe it’s a really important feature.
Our clients are used to choose date range, starting from Monday and they even could make a mistake if the week starts from Sunday, it makes them angry and less motivated to use AWS Quicksight.