Sales Opening and Closing times will happen automatically based on two rules: Minimum Booking Time and Maximum Booking Time. Those relate to close to the session and how far from the session the sales are allowed to happen.
To configure this, go to Edit > Configurations and scroll down to the Booking area.
Counting backwards from the session date and time, you must insert the value in minutes.
Minimum Booking Time – How close to the session sales for that session will stop. In the above example, that time is set to 240 minutes, that is 4 hours. Because the session is configured to 3PM (15:00) this means sales for that session will stop at 11AM on the day of the session.
Maximum Booking Time – How far apart from the session time the sales start. In the above example that time is set to 10880 minutes, that is a full 7-day week. Because the session is configured to start at 3PM (15:00) this means sales for that session will start at 3PM on the previous week, same day of the week.