The brake fan operation is a well disputed thing. Generally there is no general guideline, except the expanded checklist in FCOM.
It depends mainly on your airline's managers and/or flight instructors. You have to take into account the brake temperature, the temperatures in case of a RTO (rejected take off) and the brake wear.
There are also different brake supplier for Airbus, which have different wear characteristics. There are some guidelines on the web. Look in smartcockpit.com.
There are basically 2 different schools of thought: The first says that the brakes have to be as cool as possible, those guys switch on the fan all the time. Then there are those who want to have the brakes always within a reasonable range of temperature. They hardly ever use them, only after a RTO or an operational necessary hard brakes application. Then there are those who operate Airbusses without brake fans. They have to think a bit more, but it's also possible to make quick turnarounds.
Make up your mind which is best for you, consulting your airlines opinion leaders before
hth,
Dani
PS: In your case there is no y or n, it also depends how long is your turn around, how is ambient temp, how long is taxi time, how fast where temps rising aso.