We've known when Connally was hit for over 60 years now. He was hit at Z234. We know this from Connally himself. After viewing the Zapruder film in slow motion several times, he told the WC he wasn't hit before Z230. In 1966, LIFE magazine allowed him to study a high-quality print of the Zapruder film under high magnification. After doing so for some time, Connally reached two key conclusions:
1. He was certain he was not hit before Z229.
2. He identified Z234 as the moment of impact.
Connally had valid reasons for selecting Z234 as the moment of impact. Starting in Z238 his right shoulder rapidly collapses, his cheeks puff, and a pained expression appears on his face. The right-shoulder collapse matches Connally's earliest descriptions of the bullet's impact: he said the impact felt like someone hit him powerfully in the back with their first.
A Z234 hit makes perfect sense with what we see in the Zapruder film. It makes total sense that a bullet that hit Connally in the back would only take four Zapruder frames--4/18ths of a second or 218.4 milliseconds--to drive his right shoulder downward. 218.4 milliseconds is in the range of the speed of an eye blink. Eye-blink speed ranges between 100 and 400 milliseconds.
Similarly, the forced expulsion of air from Connally's lungs would have been quite rapid and forceful, quickly causing his cheeks to puff, just as we see in the Zapruder film virtually simultaneously with his right-shoulder drop. The cheeks start to puff just a frame or two after the right shoulder starts to drop.
Also, the shattering of 4 inches of rib bone alone was extremely painful and would have quickly caused a pained expression to appear on Connally's face. Forensic science tells us that when people experience a sharp pain, it only takes 150-300 milliseconds to react with a pained facial expression.
Jim Moore, one of the most honest WC defenders around, concludes that Connally was hit at Z236 and he basis this partly on the rapid collapse of Connally's right shoulder starting in Z238 (Conspiracy of One, pp. 198-199, see also p. 159, where he says that Connally's right shoulder "drops dramatically").
Obviously, these reactions make no sense in a Z224-hit scenario. It most would not have taken Connally's right shoulder 14 frames to begin to be driven downward, nor would it have taken 14 frames for Connally to react with a pained facial expression and for his cheeks to puff.
It is worth noting that Dr. Robert Shaw, Connally's chest surgeon, studied the Zapruder film and concluded the bullet struck the Governor at Z236, "give or take 1 or 2 frames, and that Dr. Charles Gregory, Connally's wrist surgeon, opined that the hit occurred between Z234 and Z238.
But, of course, WC defenders here cannot accept the fact that Connally was not hit before Z229 because it destroys any version of their untenable Z220-224 SBT.