I recently read about this in one of the 737 tech type apps, but I’ve never seen anything official from our operator.
A lot of guys do this when firing up a ship in the morning when it’s cold to avoid the nuclear hot air then cold then hot ad infinitum and it seems to work quite well. I’ve never had a maintenance issue as a result. If you were worried you could achieve the same effect by leaving the temp selectors alone and turning the trim air switch off.