Why plan this? See what works when you have the shots. You already know you're going to have two shots, and the second shot needs to match the perspective of the first, so there's nothing really to plan about the actual shoot. As for the mix, put them on layers and slide the opacity control until it feels right. If you prefer parts of it older and parts of it newer, rather than a single percentage slider, create a layer mask and paint in the time you want.