I dunno, man. I just haven't been able to watch the show since like season 3.
But I guess if I were to nail an official jumping the shark point, it's the wedding. Not because of the actual wedding itself, but because that's where the show should have ended.
Watching the baby episode last week confirmed that yes - the office has indeed jumped the shark. Any time a comedy show introduces a baby into the mix, it has jumped the shark.