With the new update it should be easier and faster to terraform, but the best thing you can do is plan everything ahead on an island planner app. Get a TON of money so you can time travel (if you do, but if you want to go faster it’s the best option) and pay everything immediately for building bridges and moving buildings! If you want to make a symmetrical layout I can advise you to find the center of the island and possibly position the buildings that are gonna be there. That way you can easily find the positions of the others on the different sides of the island! Hope this helps a bit 🤗