New to Airbnb, what is a weekend

Hi there. Im all new to hosting at Airbnb.

Untill now I have 2 bookings for the summer, but I have one question. If I want to open for a weekend then do I need to open for the calendar Friday, Saturday and Sunday or is it only Friday and Saturday?

I have an open weekend but I got a request for arrival Saturday and departure Monday. Im coming home on Sunday so that is not possible.

What is the best practice?