From Airbus
After landing, operate the engine at idle for 3 minutes before shutdown in order to thermally stabilize the hot section of the engine.
We consider hight thrust level operation to be thrust setting above REV IDLE or above normal taxi maneuvering power. Therefore, if MAX REV is used for landing, the three minutes cooldown period starts when reverse thrust is reduced to REV IDLE. *However, *if the landing is performed with idle reverse thrust or no reverse thrust, the cooldown period starts when the thrust is reduced at idle prior to touchdown.
During taxi, if the power level goes above the normal taxi maneuvering power, a cooldown has to be performed and the three minutes countdown starts when thrust is again at *( or near ) idle.
Cheers.