Depending on your type of business, you can work with dates, or dates and hours.
Choosing a date and time format (account-wide)
Go to your Settings in the bottom left corner of your screen
Scroll down to Date Format & Business Hours
Pick a Date and time format
Select a first day of the week
Add your business hours to prevent bookings being made during closing hours (Not available in Essentials plan)
Click Save (top of the screen)