Legal Question in Real Estate Law in California

Your tenant is right that you can only recover such future rent from them as you cannot make up by renting to another tenant plus the costs of re-renting the property early. You are required to take all "commercially reasonable steps," to find a new tenant or otherwise make up the lost rents. Given you planned to sell, however, it may not be commercially reasonable to bring in a new tenant, particularly with the new-ish state-wide just cause eviction laws. Given you will most likely want to show the property "staged" you probably should look into the cost of furnishing it with rental furnishings and listing it on Air-B-n-B. If the cost of doing that would not be commercially reasonable, you have a good case for not renting it out, but it might work out well for showing the property for sale. In any case, if you want to chase them for rent you'll want to get it listed for sale ahead of your original schedule.