3 month rental

I am not sure if a 3 month rental sits under long term rental or holiday rental. Anyway we would like to spend the winter (January through March) in Tenerife and in particular in Puerto de la Cruz. This may then lead to other things. From reading the replies to questions re long term rentals I understand the best way of finding them is to go through the local estate agents. What I'm not sure of is when is the best time to do this. If I leave it too late, there is a danger most will have gone, but too early and the agents just tell me there are no properties currently available. Any advice much appreciated. Steve