I feel your pain. I already know a fair bit about what's to come from the Second Coil of Bahamut, despite having not even started Turn 6.

But I don't think there is much we can actually do about it other than to avoid online forums for the first few days, if not weeks, after the release of a major patch.

The forum doesn't have a spoiler policy that I know of, so it's really down to individual initiative. And even then, excitement can easily get the better of us, and we accidentally drop spoilers as a result.

In other words, I think most of us do try to keep spoilers out of the lore threads, but we're only human. Accidents will occur, and there is only so much any of us can do.