I agree that 5.5 months would be pushing it a bit but it is possible to build a 15 story hotel in 6 days, so I would not be surprised if one could be built by September with the construction methods they use today.
They may well have already started the construction off site, to then flatpack...
I thought they were aiming to have it built in time for the rugby world cup in September, so to start now is probably about right if they are quick.
The way I upload an image is to click on the insert image option, then select Basic Uploader bottom right.