can't stop thinking about the alleged "time jump" now.... i'm trying to find the actual source of the widespread idea that there will be a several year time jump after the first two episodes... and from everything i can find it's like 99% fan speculation. there is ONE quote from ross duffer that is the only source every other article refers to as "confirming" the time jump in season 5 and it's this:

At least one aspect of Season 5 does sound like it’s written in stone. Given how quickly the show’s young leads are growing up, “I’m sure we will do a time jump,” says Ross. “Ideally, we’d have shot [Seasons 4 and 5] back to back, but there was just no feasible way to do that.

“So these are all discussions we’re going to have with our writers when we start the room up,” he continues. “Believe it or not, we’re still working on Season 4. We’re trying to finish the final two episodes, they’re so massive.”

... that's it. outside of that one incomplete and otherwise paraphrased quote, i can't find any other time or place they've mentioned it (please lmk and link if you find another direct quote on this anywhere else... istg i've watched a video of this interview but i can't find it anywhere).

what they have talked about in several places is the fact that they expect season 5 to be shorter than season 4, specifically because it won't require the same amount of build up that season 4 had (.............due in large part to the time jumps bwteen seasons......)

referring to season 5 in this the wrap interview:

Matt Duffer: They’re going from the beginning. There’s going to be less ramp up. And I think people will understand what I’m talking about when they see the end of this season. It’s like, we’re just going.

Ross Duffer: Yeah. Normally it’s like, oh, we get to revisit the characters in their normal lives and how they’re doing and what are their relationships like?

Matt Duffer: And they’re playing Dungeons & Dragons or whatever.

Ross Duffer: And then something happens, and then there’s an incident and it goes from there. There’s build up. There’s a lot of build-up and set-up [each season], and 5 is just going to be pedal to the metal from the opening scene. At least that’s what I remember from the outline.

and in the Happy Sad Confused podcast, they say this about season 5:

"We don't expect it to be super long, as long. And the only reason we don't expect it to be as long is because typically, or, this season, if you look at it, it's almost a two hour ramp up before our kids really get drawn into the supernatural mystery. And, you know, you get to know them, you get to see them in their lives, they're struggling with adapting to high school and so forth.... none of that obviously is going to be occurring in the first two episodes of this.... for the first time ever, we don't wrap things up at the end of four, and so... it's gonna be moving, I don't know if it's gonna be going a hundred miles an hour at the start of five, but it's gonna be going pretty fast. Characters are already gonna be in action, they're already going to have a goal and a drive, and I think that's gonna carve out at least a couple hours."

as far as i can tell (and as far as i can remember from when these came out back in july)... this is where the "two episodes" before the time jump association comes from. they never confirm when they would include a time jump, and outside of that one tvline quote from when they were still finishing season 4, they never actually "confirmed" anything. but everyone took that "i'm sure we'll do a time jump" and leapt with it