In this excerpt from our first blog, Nacho & Flor, we see so in its most common place — at the beginning of the story. And it's function here is precisely that — to let you know that this is a story of some sort.But notice that it's also used at different points within the story to mark new developments during the course of the narrative. It might help to think of it as a spoken "new paragraph" in your narrative, as in this example.
Here we see that so can also be repeated when you want to highlight certain things and keep them separate — especially complicated details like the timeline at the beginning of this paragraph. Again, it's main function here is to tell the listener to pay close attention.