I think her camera had only one lens. She wasn't filming through binoculars. What does panning have to do with the position of JFK in the last frame?
If Tina Towner was right that the first shot occurred even 3 or 4 seconds after she stopped filming then there was no early first shot miss.
Towner panning would impact the Line-Of-Sight (LOS). You're visual aid shows her LOS being straight lined.
I agree. Not only was there, "...no early first shot miss", there was no early first shot period.