You are imagining head turns that don’t exist in the case of Rosemary Willis, JFK and Nellie.
Rosemary Willis started to look away from the Presidential limo back towards the Texas School Book Depository at Z-140.
JFK began quickly turning his head to his left at Z-143.
Nellie began a quick sweeping head turn to her right at Z-144.
If you can't see this, perhaps you should get a new pair of glasses.
John Chism and Mary Woodward recalled that the last right head turn and wave of JFK was before the first shot.
The operative words are "last" and "recalled."
Regarding the former, JFK's last (as in final) wave began around Z-173, right before he passed behind the Stemmons Freeway sign and was hit in the lower neck/upper back by Oswald's second shot at Z-222.
Regarding the later, Chism and Woodward "recalled" this several hours, days, weeks, months, or years after the startling and traumatic event.
FWIW, in Z-133 we can see that JFK's right hand is near his head because he's just finished waving to someone (Woodward?), which wave he must have begun before Oswald's first, missing-everything shot half-a-second earlier at "Z-124."
https://assassinationresearch.com/zfilm/z133.jpgAnyone with normal vision (evidently not you) can see that he lowers his hand over the next couple of frames until it's all the way back down at Z-150.