If you pre-order Ultimate on the Playstation Store, you actually get the download for vanilla WO4 with it.
So if you're sure you're gonna get Ultimate when it comes out (and if you're okay with buying digital), pre-ordering it actually isn't a terrible option (for once).
Dunno if this applies to the Steam or Switch versions as well. I'd hope it does, because it'd be really stupid if it didn't.