Jack Ruby made this statement in his WC testimony:
"I did not mingle with the crowd. There was no one near me when I walked down that ramp, because if you will time the time I sent the money order, I think it was 10:17 Sunday morning."
Secret Service Agent Elmer Moore immediately corrected him and said it was 11:21, and then he made it 11:22 that Oswald was shot. And Ruby went along with the correction.
But, in the context of something that happened in the late morning, it's a lot to be off.
So, was Ruby accurate? Did he wire the money at 10:17 and then proceed down the ramp and have his incident? And then was it repeated with Bookhout an hour later?
It seems very plausible and likely to me.