Would many letters know that they are going to have a property available in December 2020? I can understand wanting to plan ahead but over a year ahead seems rather a long time? When I was renting most renters were on open ended contracts with a notice period, e.g. 1 month. Thus most letters only knew they would have a property available when the renter gave them notice. I am sure some people rent on a very specific basis but I would have thought it was the minority? For example HomeGreekHome
doesn't give you a search option to specify the date required. They are mainly advertised when they are available.