Edit > Settings : How do I change my start days for full week bookings?
1. Go to Properties > Edit > select property > Settings > Go.
2. Scroll down to the heading "Start day for full week bookings" and tick the days you want to allow as start days for weekly bookings.
3. Click Save at the bottom of the page.
To save time you can click the buttons "All" and "Flexible arrival" if you allow any start day.