I was on LiveJournal a long time ago and I distinctly remember seeing Facebook, when I first tried it after everyone couldn't stop talking about it, as an unviable alternative precisely because it didn't show exactly what you subscribed to without filtering or manipulation. So either the algorithmic timeline was always there, or it was introduced early on before Facebook got big.

I remember when it was just chronological, but it's been a long, long while since then. It might have been as far back as 2010 or earlier that change happened, but it was already 'big' by the time the change happened. I vaguely remember there being outrage because it was yet another change, along the same lines as all the design changed people also complained about, but complaining alone didn't prevent Facebook from keeping the changes.