To clear some things up

1. What does PS look like.
PS is a monster hunter. He doesn't like his name and he doesn't like his cutie mark. He also has not described himself in his journal, seriously who would? In the monster hunter games, you get to make your own character, but you don't have enough customization to actually make a unique snowflake. Just a few different faces, a few different haircuts, some skin tones, and boom, done. PS is just like that. As long as he fits the general body size of a normal earth pony, he can look like anyone you want him to look like. The cover image has a funny story: I told the guy who originally made the OC character PS to draw me a picture of a pony wearing guild trainee armor and a sword. Thats what he gave me and by no means is the definitive look of PS.

2. When does this take place
Twilight sparkle is reading PS' journal sometime before season 2. Nothing that has happened in Season 2 has happened in the story yet, including Discord. However, everything that has happened in Season 1 is canon in this story. For convenience's sake, the yearly Hunter celebration happened a few days before Nightmare Moon came back, giving Twilight a whole year to cover all of Season 1 and still not know about the tradition.
PS as a hunter was active in ponyville just a few years before. The journal can't be more than 3 years old, but it was beat up because he has to take it everywhere and had to write on it whenever he had the chance. Him carrying around the journal won't come up as a big deal until he starts taking hunts in more distant locations, which will be the typical monster hunter locations (volcanoes, jungles, mountains, the tower), and the hunts start taking several days.

3. Juggling Twilight and PS
Twilight will start having larger segments as she tries harder and harder to read the book. Eventually she'll have to engage in a few monster hunts herself, although to stay true with the show, her "hunts" would be a little more problem solving than hammers-to-the-face. Eventually I want to make it so that both stories blend together in a final climax. For the meantime though, PS will keep on writing on his experiences and Twilight will keep on reading.

I'm about to start the action part of chapter 4, but a quick word count has me almost at the 10k milestone, making this chapter much, much bigger than chapter 3.
Seriously this thing is taking over my life.