I think this is a smart strategy. They're trying to involve developers as early as possible to avoid repeating the Windows mobile mistakes. It'll also allow them to collect feedback and adjust the product before launching it. This will give it a greater chance of success.
If it's supposed to sell for the 2020 holidays, it would probably be released by October 2020 or so, so it's more like 12-13 months. Still seems like a rather long lead time.