I really don't think there should be a start for Guandu itself. I just feel it would be a bit of a pointless start, frankly most games as Cao Cao you will probably be running in to Yuan Shao anyway, lord knows I have. IMO a more interesting start would be the aftermath of Guandu starting after Yuan Shao's death in 202. So you have Yuan Shao's sons in the north fighting amongst themselves and against Cao Cao, Liu Bei in Jing province, Sun Quan still trying to establish his state after the still fairly recent death of Sun Ce. It would also be a good oppurtunity to introduce the Wuhuan. If we assume a 194/5 start would coincide with a Shanyue expansion since it would be in large part about Sun Ce's conquests(among other things), then a post Guandu start would be a good opportunity to serve as an introduction for a Steppe Tribes DLC since IIRC the Wuhuan tribes supported the Yuans.
Same thing with Chi Bi, a post Red Cliffs start seems more interesting to me then a start that starts with Red Cliffs. Sun Quan consolidating his position even further and pushing against Wei and Liu Bei trying to secure Yi Province. Ma Chao's rebellion could also be scripted and he could maybe start as a playable vassal. Not sure what else they could do though, maybe they can exaggerate the amount of fires Cao Cao had to put out after Red Cliffs to make it so a Wei player has something to do.
As for a Rise of Jin start, I'm not sure. I'm frankly just not super informed of the specifics of that event. I don't think Wei ever really split apart into full on civil war with clear territories being established did it?