I would be surprised if Star Wars Land opened in its entirety on the same day. (How could it, with Star Tours already part of it?) I think the permits show us the park's new berm will be completed by 2018, not necessarily that everything within that berm will be open.
Considering Star Wars Land and Toy Story Land were announced together, I think it's correct to call them (collectively) as the park's Phase 1 since Disney has somewhat announced it as such, and this Phase 1 will almost certainly have parts 1a, 1b, 1c, and so on. Considering the TSMM expansion, new flex theater, and Star Wars Launch Bay, plus the tremendous amount of preparatory closures, it seems to me phase 1a is only a few months away from completion.