PR – It’s good if you start it now, but just make sure to finish it in Chapter 5 for Episode Complete / story completion. It gets harder to finish it the longer you wait, but you can always finish it.
It’s much easier to just win people over throughout the chapters.
If you really want to be hardcore about it, though, you should try to get over 400 points for both companies in Chapter 1, or at least by Chapter 3 if you can. That maxes both companies at Level 5 in Chapter 5, unlocked all special games and items and gaining Episode Complete.
Each time you promote to a person and say the correct response, you get 5 pts. Saying the wrong response will get you 0-3 pts., depending on the person.
Hope I helped a bit.