Amazing to read that this is going to be done by September.
Just wondering why the skepticism. I worked construction in Dallas many years ago and from March to August of one year we put up a 10 story building. All the floors and the elevators and about half the glass work for the exterior.
The thing to remember is that once the outside is complete there will not be any weather delays. Also, the weather in Austin at this time of year is not too bad for working outside, unlike here in Chicago. They should have the outside done by the end of MArch. The grade work and putting in all new sewer lines, underground electrical and phone cabling, grade beams, and foundations is a real pain in the but and takes a significant amount of time. They have easy stuff left.