Can I set up appointment allocation so that appointments are only displayed/bookable from the next day onwards?

The general lead time can be adjusted according to your requirements. You can make these adjustments in the Settings and General Settings areas. The Lead times for appointment booking function can be found in the Advanced tab. For example, you can require customers to book an appointment at least 24 hours in advance by setting the lead time accordingly.

Please note that this setting gives your company time to respond to short notice bookings. Without this setting, a person would have the opportunity to make a booking in the middle of the night for 8am the next day.