May be not the answer your looking for, but the universal answer to the looking for idea question
Ask your players, if you take the habit to ask your player what are your plans for next time ? They’ll do most of the game prep for you. In your case you can straight up ask we’re reaching a point where the story can go in multiple direction, can you tell me the one you choose so I can plan appropriately can help you a lot
May be not the answer your looking for, but the universal answer to the looking for idea question
Ask your players, if you take the habit to ask your player what are your plans for next time ? They’ll do most of the game prep for you. In your case you can straight up ask we’re reaching a point where the story can go in multiple direction, can you tell me the one you choose so I can plan appropriately can help you a lot