Open your rooms and your guests will be able to check in only if they book a maximum of X days in advance.
For example: Double room has 3 days of Release on the 10th of may. So the room will be bookable from the 7th of may.
If you want to enable the Release enter the Calendar page, click on Customize this page at the end of the page and select All Features and then Save, as you can see in this picture:
After saving, choose the day on the calendar for which you want to set this Release and double click on the box. A window like this will open:
Insert the desired value in the box Release Days and click on Submit.
If you want to set this value for a longer period you can do the same thing clicking on Modify period.
Easy, isn't it? 😊