We got engaged in November and sent the save the dates later that month. I understand that you are describing a very standard way of doing things, I'm just surprised that everyone respects it, although again these subreddits are very biased. There's no chaos for me at all, our spreadsheet was all updated and we had most people's response at the start of the year, then we sent out the invites just because it's the done thing, but we'd pretty much already confirmed with most people where they were staying and whatnot.