Some of the users like to avoid the bookings that are made in the same day due to collision between the previous appointments. If you want to avoid the current date appointments, please make the change as shown in this screenshot.
Please download the file /wp-content/plugins/designthemes-appointment-addon/js/dt.public.js
Open the file using some editor software’s like Dreamweaver and get in to the line no: 14 approximately.
There you need to make the changes in the code as shown in the screenshot for removing for current date.