This describes the setting to automatically open online availability. You can manually open availabilities from the calendar as well, but this setting ensures future days are automatically opened.
To open up online availability:
Open: Menu > Clinic settings > Online booking settings > General settings.
Make sure Enable online booking is ticked.
Make sure that the checkbox Automatically open online availability is active.
If for instance you fill in 60 days, people could book appointments 2 months ahead.