Same day arrivals

How can I prevent late, same day arrival bookings? Last night during power cuts ( they are frequent in South Africa), Booking.com took a booking for 5 people at 9:30 pm and I knew nothing about it until I received a confirmation text at 10.10 pm. 5 minutes before the guests arrived. Luckily I was only a 5.minute drive away from the property. I want to make this impossible to repeat. The limit I want is "no same day arrival bookings to be allowed after 6:30 pm". How do I do this?

Please help !