If you want to close out or save your last available room for any Room type which is connected to an OTA or Channel Manager it can be done via the OTA Closeout Threshold setting under Inventory.

Under column, OTA Close Out Threshold you can select the number of rooms you want to protect from all OTAs. If you select 1 then that room type will automatically close out when the last room is left in that room type.

This setting cannot be variable/dynamic based on the dates. So if you choose 1 then it will do that for all dates.