You understand that there's no timeline because:
- LB and CN meet on the first day of school
- Stormy weather is set on summer (so almost an year later)
- In Evillustrator they're at school
- Nathaniel dreams Stormy weather
- (spoiler) in Glaciator Marinette says that it was her second met with Chat Noir (after Evillustrator)
- It sets Gamer, Puppeteer and (now I'm talking about season 2) Befana after those tow episodes
- Marinette turns 14 in Befana
- So she was 13 for the rest of the time BUT if we count Evillustrator as an year after Origins, she's 12 and it can't be possible.
Now there are 4 possibilities:
1) Nathaniel can see the future
2) Marinette is a lot more mature for her age (high school at 12? WTF? Seriously?)
3) Season 1 lasts for more than 1 year
4) There isn't any timeline.
Tell me if I missed something
However, it's fun trying to create one.