Yeah, funny enough the first fanfic I ever wrote was written a year before my main fandom ended.
But yeah, this time seems to be right after it ended. In fact I technically predicted the ending of the series in some ways. I wrote a story suggesting a foursome of sorts, and apparently that happened in the show.
The end of a show can be a huge plot-bunny generator. It frees you to take the characters in any direction you want without any danger of your story being AUed by something that happens in canon later on.