The time estimates by witnesses are not likely to be absolutely accurate. Did Bonnie Ray Williams look at his watch? Did BRW wear a watch?
Was Oswald hiding quietly in the Sniper's Nest hoping BRW would leave the 6th floor before the President drove by the TSBD?
There are timestamps that have been repeatedly posted that show that Williams likely did not vacate the Sixth floor until at least 12.25.
Mr. BALL. Did you stay there?
Mr. NORMAN. Well, we stayed there I believe until we got the news that the motorcade was coming down, let's see, is that Commerce, no Main, because Commerce- we went back in the building, James Jarman and I.
A timeline of the Presidential Motorcade taken from Dallas Police Radio logs shows that the Motorcade got to Main about 12.24pm. Aslo Jarman estimated the time they left the front of the TSBD to be 12.20-12.25. They walked approximately 200 ft to the west elevator and about 160 ft to the SE corner of the 5th floor. This would take about a minute at 6ft per sec walking speed. The elevator took about 45 seconds to reach the 5th floor. They could have been in position on the fifth floor about 2 minutes after departing the front steps and may have been in position around 12.25 or slightly earlier depending on the accuracy of the broadcast. Williams claimed he joined them after they arrived.