For Doctor Who, I'll use the TV show, comics, audio stories, and novels/short stories to make the Doctor's past journeys more sense.
A lot of time had past since the Doctor, Bill, and Nardole landed in Los Angeles. And since that time, they've been exploring the different wonders of the city until the time of the concert, which was tonight. The Doctor explained to his two companions the numerous times he visited Los Angeles and the many adventures he's done there.
"So there were mammoths and sabre-tooth tigers in pre-historic times, exactly where Los Angeles was going to be?" Bill asked the Doctor after talking about one of his experiences with a previous companion.
"Well, my friend and I encountered one of each of them," the Doctor explained.
"That must have been a crazy experience for you two," Nardole added, amazed.
"Oh it certainly was," the Doctor said.
The Doctor, Bill, and Nardole made their way to the club where the reunion concert was held at and there were plenty of fans waiting there too, most of them in their 20s. About a half-hour later, a limo pulls up near the club and the crowd of fans erupted in screams, which startled the trio.
Nardole, covering his ears, said, "Wow! These guys really are excited to see Vince Vincente and Ladyheart, huh?!" He tried to speak up over the loud fans so the Doctor and Bill could hear him.
"Well," the Doctor said, speaking up as well, "From what I've read and heard of, those guys were a big deal way back in the day!"
While waiting to get in the club, the Doctor noticed four men: one tall and one short, both wearing leather jackets, one wearing a trench coat with a tie, and the last one wearing a dark coat. "Hmmm," he hummed, still looking at them with a stern look. It was then that Bill saw the Doctor looking suspiciously at the group of men, curious about what did he see in them.
"What is it?" questioned Bill, as she looked at the four men as well. "What is it about those guys that's making you so wary?"
"I don't know," the Doctor replied, "but I have a feeling that something's going to happen, and those four will be involved. I don't know when, or why, but something will happen."
It was at that moment that one of the men from the group noticed that the Doctor and Bill was looking at them for some reason and they just as quickly looked away.
"You think they saw us?" questioned Bill.
"Probably," the Doctor replied, "but I doubt they'll care about us." The Doctor was still suspicious about the four men and wondered if they were planning something terrible, like ruining the concert.
After some time, Vince Vincente came out of the limo and the fans erupted into screams again, causing the trio to ccover their ears again. And after Vince entered the club, the crowd, along with the Doctor, Bill, and Nardole, prepared to enter as well.