Looks like Hobby's International addition will take 2 yrs according to the the Biz Journal.
"According to a presentation shown to Houston City Council Feb. 4, Houston’s airport authority plans to build a new parking garage and a new concourse, expand its terminal and make roadway modifications at Hobby to accommodate international flights. The project is scheduled over the course of more than two years."
"During the terminal expansion, HAS plans to build a new ticket counter, add six additional security checkpoint lanes, add five new arrival and departure gates and add a new Federal Inspections Services facility for international travelers to go through Customs and Border Protection. The FIS facility itself will have its own baggage claim, 16 passport inspection stations and allow for 400 to 800 passengers to travel through it during peak hours."
"Construction on the project is expected to break ground this May, and vertical construction is expected to be complete in September 2015."