Originally Posted by
Chesty Morgan
It usually starts as soon as the autopilot is disconnected.
Any FOQA/FDM data, (always de-identified), will show this - with AP engaged, there is minimal flight control movement until disconnection.
Whether such movements have a material effect upon the flight path can also be examined, but perhaps all the fore-aft and/or left/right movements cancel one another out. Besides, mass alone would tend to dampen changes in the flight path, (but not pitch/roll attitude!).
PJ2