It's been a while, so consider everything "if I remember correctly", plus best practice may have changed.
The reason that you're seeing conflicting advice, is that the Nitrogen Cycle wasn't understood until relatively recently: a lot of outdated advice persists.
To establish my tank I added a small pinch of fish food, before adding a pair of Zebra Danio: perhaps over 7 days.
But you need to test your water much more often, to begin with: if your tank is going bad, you need to be on top of it.
You're right about changing the water a little and often, but I think I changed more, more often: maybe one third/25% on a weekly schedule? Quite shaky on that point.
Follow the same approach to adding fish (no more than half a dozen small fish at a time).
Plecos get big, perhaps look at Glass Catfish? 130 litres is good for bottom feeders, a couple of shoals of mid/top-level fish and your highlight(s).
I may still have some books you're welcome to: remind me at the weekend, if you like.