You are from further ahead in the timeline. Things happen very quickly once Valentine reappears.

[ Not that he was there for most of it, but he's heard the story, repeatedly, with various levels of exaggeration. ]

Alec and Magnus are both from before any of it. Not entirely sure of where Isabelle is, chronologically. My timeline is different enough from yours to be frustratingly confusing, but I am several years past the Mortal War.