If you want to limit how far in advance clients must book an appointment (to prevent last-minute or same-day bookings), you can do this using the Latest Appointment/Class setting found in the Service & Class Time Display panels (Settings > Time > Service Time Display or Class Time Display). The default setting for your account is decided on these panels.
The Latest Appointment/Class setting defines how much advance notice is required for clients to book an available time. It prevents clients from seeing or booking any time slots that fall within that cutoff window.
Customizing for Specific Services or Classes
You can also customize this setting on a per-reason basis with the Time section of each service or class profile. Adjusting this setting on the reason profile will disconnect this option from reading the account's default and allow you to set a different Latest Appointment range for that one option.