@Liz-and-Ivan0
Advise to decline the booking request. Always look at the guests reviews. Ask them to send in a re-request for booking after they have their dates firmed up. Also, make sure that your cancelation policy is set to firm and that full payment is due at booking.
For us, It was either AirBnB or VRBO that once allowed someone to book without paying for the last minute booking in full. We declined until which time the request was made and paid for in full. A reminder is sent to the guest informing them of our cancelation policy and that last minute bookings are not refundable.
We have about 3% of our bookings classified as last minute which for us is no less than 2 days before the booking starts. On the last minute request for booking, we ask a lot of questions before accepting.