I think that the story about Ruby going to check out the wreaths before going to Western Union was information that was fed to him. If I recall, this is something that has come up in the past? It was probably told to him by Howard who said that it would look better for Ruby's defense if his time of arrival at the police station seemed spontaneous.
I posted the link because the first few minutes show the scene outside of the County courthouse in Dealey Plaza, which is close by the assassination site and the wreaths Ruby would have looked at. Notice the huge crowds? Ruby never mentioned anything about the hundreds of people or having his curiosity "aroused" by the commotion, like he did regarding the much smaller scene near the Main Street ramp.
Incidentally, the announcer mentions how much security there was by county, with an officer stationed every 15 feet along the street (and the film shows it). However there was only one officer on the Main street side of the DP station (with at least 6 on the Commerce street side). It's obvious that they planned ahead of time to say that is the way Ruby got in and that it would sound reasonable if he eluded just one officer.
I agree with all that, Amy, but I also have no doubt that Ruby did enter that way, through the Main Street ramp. And that's because if it was anything else, any other way, then he had to have to have help, and he had to have bad intentions, and neither one of those were true. But, I have long doubted that Ruby went to see the wreaths on Sunday morning, rather, I think that was added to the story to kill time. Why would he go there on Sunday when he went there on Saturday? He had to go two days in a row? That isn't likely at all. And, he provided no details about the Sunday visit. So, I agree that it was probably fed to him, and he came to add it to the story.
I believe that Ruby got there early, perhaps 10:00 or 10:15. Some cop other than Roy Vaughn, an insider, was stationed at the ramp, and he and the "spectators" were all there to coax Ruby down the ramp. It was definitely after 9:30 because Dr. Bieberdorf said he was ordered out of the garage at 9:30. Lt. Sam Pierce was pulling out at the time-alone. And as soon as it was over, Ruby was rushed upstairs, and Vaughn was put on watch at the head of the ramp. That is my current thinking.