Ok, I got into your first 4 pages(or first act) and you're missing a few things for starters.
First off ya need to start with "FADE IN:" Nathaniel also needs a description, is he short, tall, fat, stocky, skinny, muscular? Ignoring the to do list feels a little passive, maybe have him watching tv or playing a game instead? I might recommend that don't have him react to the first doorbell ring. I think it'd help establish his laziness a little further.
I think you have Nate saying a little too much after opening the door and seeing no one is there. Keeping it just at "This is why I hate people" feels enough to me. Its amusing and says a lot about him.
I also think that the older versions first lines are a little too on the nose though, maybe just keep it at "god, this place is a mess".
The first lines of the conversation with the two is kind of redundant I think. I see what you're trying to do, but I might recommend rather than go for a bit of banter now, have their first conversation be directly to the point. You can add some banter later, but you've established a mystery right now. Who is this man and how did he get in here? Focus on that for the time being.
Your dialogue has a lot of meaningless words that take up a lot of space and share little to no information . Don't worry, We've all made the same mistake. I'm only a few steps away from where you are and still fumble with it. For example:
Who are you?
That’s a reasonable question -
Of course its reasonable. I rent
this place , its my property -
Actually its the councils if you
really want to get technical."
This back and forth takes up about 1/5th of a page and tells me nothing about the characters, other than they're kind of snarky. The older version is there with a goal, and that needs to be his focus. This is why I said have your characters be direct and to the point for now and add some humor later.
The older version shows up, but doesn't reveal he's Nate from the future. As it is right now, he's just some guy who shows up and kind of knows the younger Nates past. But I was waiting for him to show, not tell. Have him show off a tattoo they both share, or a scar, something visual. Even a photo of old friends. Even if the younger version rejects this at first, we the readers can go off of this information and draw our own conclusions.
So far the protagonist is lazy and shows little to no character and the guide falls into the same trap. The stakes are currently "to save you from your dismal way of life.". As of right now, those stakes are pretty unengaging because Nate has nothing to really lose since theres so little of who he is told in the script.
You gotta give us more information about your protagonist. Is he a slob with a good heart? A drug addict trying to make amends? Someone who wants to do better but doesn't know how? We need to be invested in him but right now there isn't much of anything to go off of.
What are your protagonists stakes if he fails? Do a bit more showing and less telling in your first act. Once you get some of this stuff sorted out the script will feel a lot more engaging and you'll hit that sweet spot as a writer. Keep trying!