We had quite strict estate guidelines to adhere to. This included specifying the exact letterbox, and designing our entire garden front and back which required 3 X advanced (3m) native trees in the front, 5 X advanced (3m) native trees in the back and 20 native plants.
Very hard to decide a year out from even being in the house.
That's a lot of trees, hopefully they don't have issues with the roots!
I think it'd be a lot easier to decide what to do with the landscaping when we can actually see what the house and yard looks like, I guess the developer wants to be able to say that you have agreed to doing something decent with your front yard at least so it has to be done in advance.
We actually kind of * and made the trees this type of pencil pine down the side of the driveway and down the side of the backyard. It is a native and doesn't take up a lot of room allowing us to still have the freedom with the rest of the yard.