If your concerned about the turbo cooling down before shutting it off...I would install a pyrometer so you can monitor how cool its getting. On all the upgrades that we do...I pyro is one of the guages that is installed. The pyro probe is installed in the exhaustmanifold between the engine and turbo. The big rigs have the probe after the turbo. It is 200* cooler post turbo than it is pre turbo. What I tell the my customers that as long as the pyro reads 300* or lower it is fine to shut it down. What your trying to avoid is coaking the oil on the bearings in the turbo. This leads to a very short life span of the bearings.
Also getting the motor warm will help with pollution. A cold diesel engine will not run effecient until it gets heat in the cylinders. They wont build heat until you are working them!
Owner: The Diesel Bunch Performance Diesel
97 Dodge Twin Turbo Cummins 5 speed,ladder bars,US Gear Exhaust brake