This link shows it can easily get done in 2 years so if that's true, they could begin breaking ground as late as 2014 and would be completed by April 20, 2016. It could even be expedited, completed within 1 year which means construction could begin as late as April, 2015 to be completed on time.

http://raptureintheairnow.com/histor...ng-to-build-it