This question already has an answer here:
Sleeping in Light is the final episode of the television series Babylon 5.
There is a series chronology posted on the Wikipedia page for the series, which includes related movies and series. According to this chronology, season 5 (the final season) takes place in 2262, but the final episode (Sleeping in Light) takes place in 2281. In between the next-to-last episode of the last season and Sleeping in Light, there are no less than four films and two spinoff series.
According to the good answer on what order the movies and shows should be watched in, one should watch Sleeping in Light ("The rest of Season 5") between The Legend of the Rangers and A Call to Arms. The first takes place in 2265, the second in 2266. What's the rationale for watching it here? I've left a comment on that answer, but have received no response, and I think it's a topic worthy of its own question.
I've followed that suggested watching order all the way through The Legend of the Rangers, but am stuck trying to decide whether to watch Sleeping in Light now, or after watching everything else.