Oh hey, sorry for taking so long to reply to this!
At this stage we're still unsure what (if any) pre-release builds will be available. We may do an early closed alpha or beta or the like, and we also MAY end up doing Early Access, but it all depends on how the game looks and plays in the coming months. Right now the open world itself is quite empty - we've got most of the mechanics in there, now we're just populating it - so we'll see how it's looking a few months down the track.
Oh and if you want to definitely be told when and if any early builds happen, jump on the mailing list. Those people will be the first to know!