@Sarah22 - you don’t need to do anything as the calendar defaults to unavailable- white-
and sitters can choose to update with the dates that they are available-Green- / blue
Most hosts don’t understand that when the calendar dates are white that means unavailable so invite sitters anyway -
or they don’t look at the availability calendar -
Also the search function ( find a sitter ) for hosts ask them to input the dates they need a sitter but then the list produced includes sitters whose calendars show that they are unavailable- so no wonder hosts send invites !
A simple key that explains the calendar and displays on the calendar page would be a good improvement and has been asked for many times.