Seasons start and end?

I’m trying to do a Big Project related to. What I do lol and I have a question.

Is there any place where they officially say when a new season starts and ends? Specifically season 1 and 2, I can’t find a place where they say that. I know where season 2 ends, it ends with The Emmy Losing Episode.

The ‘Am I The Asshole’ episode kicks off Season 3, but I need to know when Season 1 ends and Season 2 begins, please. For the sake of numbers, in the name of math, for the not-official but not unofficial spreadsheets of mine. Please 🙏