24hr ahead booking (or block booking on current day)

Hi
got the plugin and appointments set up - had a few issues with very erratic behaviour and randomly disappearing from page, but works now that have turned off the built in caching.

Is there a simple way to exclude the current day - or exclude next 24 hr from availability in the calendar? Client using the booking system can only check appointments in mornings so having someone book for an immediate time slot could cause problems.

Thanks for your help