Nintendo had the Zelda timeline planned out in an "enormous document" as far back as 2003, but Shigeru Miyamoto said it's actually "not that important to us"

The Legend of Zelda timeline was a matter of intense debate in the forums I frequented as a young Nintendo fan, but by the time it was ultimately revealed in the 2011 Hyrule Historia book, I had moved on to caring about topics other than whether there were multiple Links and Zeldas. But Nintendo had a secret document detailing the whole thing all along – even if Shigeru Miyamoto himself didn’t care about it all that much.

“For every Zelda game we tell a new story,” Miyamoto explained in a 2003 interview with the Swedish Superplay Magazine, which was translated and hosted on various corners of the old internet. “But we actually have an enormous document that explains how the game relates to the others, and bind them together. But to be honest, they are not that important to us. We care more about developing the game system.”