Answering calls from developers, Valve have tweaked Early Access game pages to allow developers to add a full release date. Just like Coming Soon pages can list an exact date, or a period where it may release, Early Access games can now do this too.

Should hopefully help prevent a little confusion for potential purchases, and just allow developers to be a bit more upfront about how long it might take. Or, if a game is releasing soon - just a simple way for you to see. Developers aren't forced into using this though, as plenty won't know when it will be finished.