You can configure the "Same-day Booking" scheduling window to be for a day so that no one will be able to book an appointment with you for the same day. To set it up, please follow the below steps.
Here is a quick video:
Here are Step by Step Instructions:
Go to Booking Pages.
Select a Booking.
You will see these Settings:
Step 2. Click on "Notifications" to modify when your customers can latest book your service.
Step 3. Select by when you would like to allow your customers to book the earliest service with you.
For Example - If you want no one to book an appointment with you for the same day, then select "tomorrow" from the drop-down option.
Step 4. Don't forget to save your new settings!