One thing is certain beyond any rational, excusable doubt: JFK begins to react to being wounded long before Connally begins to react to being wounded. JFK starts to react at right around Z200, as does Jackie. JFK's and Jackie's reactions that we see in Z224 begin in Z202. Starting in Z202, Jackie snaps her head from left to right to look at JFK, and she's still intently looking at him in Z224.
To all but those chained down by the single-bullet theory, it is obvious that JFK was hit by no later than Z196, and we know Connally was hit at Z234 because he told us so after carefully examining high-quality prints of the relative frames under high magnification, which makes perfect sense because he clearly starts to react in Z238.