There seems to be a weirdly common misconception in which people think apple is working on their new device designs right up until the moment they release. Reminds me of the Series 7 where people think apple "last minute" changed the design as if it wasn't settled 6+ months before it came out. For iPhones they're probably over a year in advance. 2 Years doesn't sound that odd especially considering supply chain issues.
I understand how it works, and know there’s plenty of time between all these steps. Just feels odd we’ve been seeing rumours of an OLED iPad for some time, and now that final prototypes are complete its still 2 years away.