Pratt guidance is for the CT rinse to be done at the end of the day's flying to get rid of the contaminants and reduce sulphidation etc.
Some/most folks do it the following morning to avoid either having to wait for the installation to cool down or pull out the blowers to force cool so that the boys can get to the pub a bit earlier.
I am aware of one large PT6 operator which has done this for some years without any adverse findings at O/H.