While one is always entitled to engage in thought experiments, a thought experiment taking Vicki Adams' story at face value seems a stretch to me in light of the fact that Sandra Styles, her companion, always said she thought Vicki's time estimate was at least somewhat off and, more importantly, was adamant that Shelley and Lovelady were not there. Occam (or Ockham, if you prefer) tells me a more plausible thought experiment has Vicki conflating her and Styles' trip down the stairs with a slightly later encounter by her with Shelley and Lovelady when they reentered the TSBD. But, hey, that's just my and Occam's little thought experiment.

Bart Kamp summarizes what Styles repeatedly told Barry Ernest here: http://www.prayer-man.com/tsbd/sandra-styles/. Sean Murphy also followed up with her after Ernest's book came out. I also found a long discussion at Greg Parker's forum where the sentiment seemed to be that the "Shelley and Lovelady" question and answer had been fiendishly inserted into Vicki's actual WC testimony precisely to make it seem that she and Styles must have left the fourth floor window later than she thiought. Greg seemed to find this unlikely, and my thought experiment doesn't require any such shenanigans by the WC; in mine, the two cuties can have come down the stairs however quickly you like, with Vicki simply being a bit off as to when she saw Shelley and Lovelady.

(Lots of Sandra Styles' stuff for sale on eBay. Don't miss your chance: https://www.ebay.com/itm/175838680679. I may have got burnt on $1200 worth of Bogus Imposter Haygood autographs, but this Styles stuff is the real deal.)

Adams' version of events is supported by the Tom Dillard pic, the Stroud document, the fact she never encountered Truly and Baker (and vice versa) and Baker's observation of two white men hanging around the area Adams said Shelley and Lovelady were and at the same time, roughly 60 seconds after the shooting.
She is a totally credible witness of impeccable character.

Just for argument's sake though...
Let's say you do have some intelligence and can manage this rudimentary thought experiment, you must agree that the only way for Shelley and Lovelady to reach the area near the freight elevators within 60 seconds is to enter the building through the front entrance moments after the shooting.
You must agree, as part of the thought experiment of course, that taking Adams' testimony at face value would disprove your identification of Shelley and Lovelady in Darnell.

While one is always entitled to engage in thought experiments, a thought experiment taking Vicki Adams' story at face value seems a stretch to me in light of the fact that Sandra Styles, her companion, always said she thought Vicki's time estimate was at least somewhat off and, more importantly, was adamant that Shelley and Lovelady were not there. Occam (or Ockham, if you prefer) tells me a more plausible thought experiment has Vicki conflating her and Styles' trip down the stairs with a slightly later encounter by her with Shelley and Lovelady when they reentered the TSBD. But, hey, that's just my and Occam's little thought experiment.

Bart Kamp summarizes what Styles repeatedly told Barry Ernest here: http://www.prayer-man.com/tsbd/sandra-styles/. Sean Murphy also followed up with her after Ernest's book came out. I also found a long discussion at Greg Parker's forum where the sentiment seemed to be that the "Shelley and Lovelady" question and answer had been fiendishly inserted into Vicki's actual WC testimony precisely to make it seem that she and Styles must have left the fourth floor window later than she thiought. Greg seemed to find this unlikely, and my thought experiment doesn't require any such shenanigans by the WC; in mine, the two cuties can have come down the stairs however quickly you like, with Vicki simply being a bit off as to when she saw Shelley and Lovelady.

(Lots of Sandra Styles' stuff for sale on eBay. Don't miss your chance: https://www.ebay.com/itm/175838680679. I may have got burnt on $1200 worth of Bogus Imposter Haygood autographs, but this Styles stuff is the real deal.)

Good presentation, but not quite up there with the legend Michael Brownlow yet. Need to jazz things up. Need more pazazz 

Yes, I need to tell a few porky pies and when challenged on them, simply claim I saw proof in the Dallas Police city records.

Taking the earlier difficult shot gave Oswald an extra chance to hit JFK. He  could still be able to take the easier later shots if he missed which he did. It could be argued that by taking the early first shot, he could have cost himself a chance at the later shots, but that didn't happen. That was a decision Oswald had to make and the fact someone else might have made a different choice proves nothing. Given that Oswald eventually succeeded in what he was trying to do, I see no reason to second guess his choice.

Oswald's first, missing-everything, shot, was at "Z-124," half-a-second before Zapruder resumed filming at Z-133, as evidenced by the fact that:

1) Secret Service Agent Glenn Bennett (who said he saw a bullet strike JFK in the back after he heard a "firecracker-like" sound) started leaning far to his right around Z-150 to see around Dave Powers to see if JFK was okay.

2) Secret Service Agent George Hickey started leaning over the side of the car and looking down at the pavement in Z-146.

3) Rosemary Willis glanced at the TSBD while she was running and looked in that direction after she stopped running.

4)  All five passengers of the limo quickly turned their heads (in different directions) between Z-140 and Z-150.

5) Mary Woodward said there were three shots, that the first shot sounded like a backfire, that JFK and Jackie turned their heads in response to it, and that the first shot missed everything. (JFK turned his head quickly to his left starting in Z-143; Jackie extended and accelerated her already left head turn to be "captured" in the Z-161 Robert Croft photo with a concerned look on her face.)

6) In Z-180 we see that John Connally has turned his head back far to his right in his futile attempt to catch a glimpse of JFK (who has turned his head far to his right and is waving to Mary Woodward) over his right shoulder.

I can detect nothing about Secret Service Agent Glen Bennett's position from the Z-153 frame. The image is too small and blurry to decipher anything about his position.

Can you see the oblong-shaped, kinda vertically aligned flesh-colored object about the size of a football in the passenger's side back-seat of the Secret Service Follow-up car in Z-150 and Z-153?

Hint: That's Glen Bennett's face, and it's leaning much farther over to his right in Z-153 than it was in Z-150.

Why?

Because he was trying to see around Dave Powers in front of him to see if JFK was okay after Oswald's first, missing-everything, shot, at "Z-124," half-a-second before Zapruder resumed filming at Z-133.

PS Note that Secret Service Agent George Hickey, opposite Bennett in the back seat, leaned over the side of the car and looked down at the pavement (he evidently thought a firecracker had exploded there), in Z-150 and especially in Z-153.