So, we know that next week is the combat preview. I'm guessing that the previews we have left will be one for special abilities and terror and other effects, and the like, then two for upgrades and army building, one per faction, which would include the heroes.
Assuming 4 more after Combat, the previews would wrap up mid February. A week after that for the Wave 1 announcement, I am guessing it will include the command units and spell casters from the preview.
If the delays that led to the cancellation of events at Adepticon are accurate, I would guess it will be "on the boat" around the time previews wrap up, and shipping around Adepticon.