Please remember in any case that “available as of” only indicates the respective earlierst moving-in date.
You will also very often be able to rent the property in question as of a later date (e.g.: available as of 15.01.; rental only as of 01.02.). As long as the gap between the two dates doesn’t exceed a certain extent, such processes are quite common.
The tolerance usually corresponds to the temporal modalities of the enquiry: the longer a stay is intended, the more likely you will be able to start the tenancy at a later date.
Please keep this factor in mind while choosing and considering the dates.