You can easily modify the default arrival and departure times that are visible to your guests.
1. Go to Menu > Settings > Services > Bookable services > Choose respective service (e.g. Stay)
2. Click on your stay service.
3. Scroll down and open the Reception tab.
4. Under Departure time and Arrival time, enter your default check-in and check-out times using the 24-hour clock (military time).
For example, if the default time for check-in is 3:00 PM, enter 15 hours 0 minutes under Arrival time.