I bet the 6 month period is paid DLC content.
it makes perfect sense, being just shortly before the 'main game' so pretty much ALL the pre-made contents can be recycled .
And they can decide which quest NPCs to reuse based on player feedback from the main game.
it's even possible that Jackie becomes the main playable character in the DLC .
So yeah, first a large DLC covering the 6 months as prologue , so we get to know more about Jackie, and it's easier to make because of the reused map contents and then a second smaller DLC to the space station .