Wrong.
From Kellermans' report, 11/29/63: "We were still traveling at the normal rate of speed of from 12 to 15 miles per hour when I heard a noise, similar to a firecracker, exploding in the area to the rear of the car, about 12:30 p.m.
Immediately I heard what I firmly believe was the President's voice, "My God, I'm hit!" I turned around to find out what happened when
two additional shots rang out, and the President slumped into Mrs. Kennedy's lap and Governor Connally fell_to Mrs. Connally's lap. I heard Mrs. Kennedy shout, "What are they doing to you?"
Specter was apparently not in the room at the time he wrote this.
Greer, the driver, said this:
Mr. SPECTER. Now, how many shots, or how many noises have you just described that you heard?
Mr. GREER. I know there was three that I heard--three. But I cannot remember any more than probably three. I know there was three anyway that I heard.
Mr. SPECTER. Do you have an independent recollection at this moment of having heard three shots at that time?
Mr. GREER. I knew that after I heard the second one, that is when I looked over my shoulder, and I was conscious that there was something wrong, because that is when I saw Governor Connally. And when I turned around again, to the best of my recollection there was another one, right immediately after.
Mr. SPECTER. To the best of your ability to recollect and estimate, how much time elapsed from the first noise which you have described as being similar to the backfire of a motor vehicle until you heard the second noise?
Mr. GREER. It seems a matter of seconds, I really couldn't say. Three or four seconds.
In his same day report, Greer said he heard two shots.
Link/source:
https://www.jfk-assassination.net/russ/testimony/sa-kelle.htmLink/source:
https://www.jfk-assassination.net/russ/testimony/greer.htm