That's not what I mean by recurring. My other examples, Andorians and Cardassians, also had subsequent appearances in the shows they originated, but were never major players, nor were they intended to be, until ENT and DS9; and for the Borg, not until VOY.
So you wanted and entire series of exposition before TNG to set up the Borg?
Again, that version of the Borg was scrapped by the time Q Who came along. The Borg that we see in Q Who were created for Q Who only. They were never intended to replace the Ferengi as TNG's recurring bad guys as the original Neutral Zone concept was. That concept, along with several others from that era, were aborted by a writers' strike. Those Borg were supposed to come from the Alpha Quadrant, not be introduced by Q 7000 light-years away. The whole point was for Q to show them something terrifying that they had never encountered before, not "those guys you encountered in season 1".
Plans change all the time bu it does seem clear that the encounter at the Neutral Zone was meant to herald their arrival.