We have not seen him appear or awaken, he was just there. But there is this possibility that he is as much a "primal" as our Good King. Bahamut retained his form when fought in the Burning Heart (albeit smaller maybe due to technical reasons/being of appropriate size to be fought by players.) If that dragon on the logo is in fact Midgarsormr, then he is a primal and was one during the opening cutscene of 1.0. I know the devs said he wasn't a "primal", but that was before the broadening of the word's definition. Who knows, maybe Moenbryda will come up with a new name for those creatures in the coming patches.