Oswald didn't have the option of working the bolt repeatedly just before shooting, because he is in the sniper nest by 12:24
No , That's not correct.....Lee was in the first floor lunchroom at about 12:26 whe Jarman and Norman passed by on their way to the fifth floor....
right
barring the random coincidental selection of Norman and Jarman by Oswald as probable, then we are left with where Oswald could have seen or heard Norman and Jarman, IF Oswald were the shooter AND also, able to get into the snipers nest by 12:24 without being seen by Bonnie Ray Williams leaving from that window by 12:22, otherwise, the box cannot be placed in the window by 12:24 unless BRW placed it, which is highly NOT probable.
The only place remotely probable for Oswald to be hiding, to be able to both hear Norman and Jarman coming up the staircase, and also see or hear BRW using the elevator and going down to 5th floor, is that Oswald hides on the mid level of the 6th floor staircase going up to the 7th floor.
He could have heard Norman and Jarman on the staircase one level below,, and he could hear and possibly see thru the elevator shaft, BRW using the East elevator.
But this would require Norman and Jarman be AT their windows by 12:20, and BRW joining them as Jarman said "several minutes later, at approx 12:23. so as to give Oswald at least 1 minute to cross over the 6th floor and put the box in the SE 6th floor window ledge by 12:24, just before the Bronson film begins.
But even Jarman and Normans LATEST estimate of their STARTING to leave from front of the TSBD is 12:20, so this makes it nearly impossible for the above "Oswald hiding" scenario.