The whole area from Mama Melrose to LMA is going to be the staging area for the first phase of construction, which will most likely be the clearing of the marsh land for the construction access roads and then possible parking lot work as well as, potentially, some SW work where the parade facilities are now.
Personally, I think we're still a year away from any work on the actual SW Land, at least. You'll know when it's beginning when you hear a closing date for Indy and most everything else around Echo Lake (Frozen Ever After, 50s Prime time, etc.).
The area designated for staging is perfect because, besides the theater, it's completely void of major structures and puts them within easy access of the roads and the area where the first part of construction will begin.
That is, besides TSL, where construction will be going on at the same time.
I doesn't make sense to me that this would be a staging area for the work, since that work would be taking place on the other side of Studio Dr.