This simple and common sense point is somehow overlooked by those trying to push an early missed shot.
The Sniper's Perch is the arrangement of boxes supposedly used by the shooter to rest his rifle on during the shooting.
This means the boxes were arranged BEFORE the shooting.
This means the shooter had already planned out what he was going to do BEFORE the motorcade arrived.
The arrangement of boxes tell us the shooter had decided that the 'kill zone' was going to be towards the triple underpass.

This is confirmed by the testimony of Ronald Fischer.
Fischer and his work colleague, Bob Edwards, were stood directly across from the TSBD building on Elm Street waiting for the motorcade. Edwards noticed a man on the 6th floor who seemed to be in a cramped, uncomfortable position, he pointed the man out to Fischer and made a joke about him. Something about the man made an impression on Fischer:
"And I looked up and I watched the man for, oh, I'd say, 10 or 15 seconds. It was until the first car came around the corner of Houston and Main. And, then, when that car did come around the corner, I took my attention off of the man in the window and started watching the parade. The man held my attention for 10 or 15 seconds, because he appeared uncomfortable for one, and, secondly, he wasn't watching-uh---he didn't look like he was watching for the parade. He looked like he was looking down toward the Trinity River and the triple underpass down at the end-toward the end of Ell Street. And--uh--all the time I watched him, he never moved his head, he never-he never moved anything. Just was there transfixed."
This is pretty much what the shooter was staring "transfixed" at:

The shooter knew exactly what he was going to do before the motorcade entered Dealey Plaza.
The area circled in the pic above is where the limo is moving almost directly away from his position. There would have been minimal lateral movement of the target.
He would have been aware of the oak tree and would have taken his first shot once the limo had moved into the open space as shown above. Once the limo had cleared the oak tree he would have had more than enough time to get multiple shots off while the target was in the 'kill zone'.
The idea that he was on his feet trying to shoot through an impossible gap in the half-closed window in an area where he had nowhere to stand is plain stupid.
He knew when he was going to take the first shot before the motorcade reached Dealey Plaza.
That he was going to wait until the limo was in the kill zone circled above is yet even more evidence that the first shot was taken at z222/z223.
Question is did the shooter test out his angled box platform by actually placing his rifle atop these boxes in the prelude time he has. I’ve got the shooter not getting to window any earlier that 12:23 because of Jarman WC referring to he and Norman having not started to return to TSBD until after they heard a radio on a DPD motorcycle reporting the limo about the reach Dealey Plaza. That time was supposedly 12:22. And if Norman and Jarman therefore do not get to their 5 th floor windows till 12:23, then BRW joined them, then BRW had be out of the SN for sure by 12:23.
If BRW left at 12:20 ( not seen again by Rowland after looked up again about 5 minutes after the 12:15 sighting) then where did BRW go between 12:20 and 12:25? Was he just walking around on the 6th floor for 5 minutes?)
If BRW left at 12:16 completely from the 6th floor , there is more time for the shooter to have positioned the boxes and possibly read out his platform by resting the rifle on without being caught in Hughes or Bronx film ( started approx 12:25)
BRW time is the big variable here and it was at the least a mistake by WC to nail down WHERE he was between 12:16 and 12:23.