when's it gonna be completed?
theamazingbrentwood.com home page updated, saying coming Spring 2019. Brentwood One owners would probably be completing their closing process around that time, maybe a bit before. I bought in Solo and there were several delays, so I doubt closings would happen before December 2018.
How come residential owners get to move in first before commercial tenants?
It's probably because the commercial tenants don't want to open until after a strong residential/customer base has moved into the towers. Retail sales per square foot are likely to be higher if the stores open after residents have moved into the 1st tower.