I think when Bella's eyes open up for the first time as a vampire, I imagine it like Bella's in the bed and her eyes snaps open and it's crimson :))
I think it should end when Bella's heart stops and Jacob sees Renesmee.
I can just imagine seeing his look of heartsickness changing into utter joy when he saw her.
I think they should stop stop at wwhen bella open her eyes
It should NOT be two movies anyways, but since it is....
I think they will split when Bella is turning into a vampire, or maybe when she first opens her eyes.