The Square Kilometre Array telescopes have recently started their construction phase, after years of pre-construction effort. The new SKA Observatory (SKAO) intergovernmental organisation has been created, and the start of construction ($\mathrm{T_0}$) has already happened. In this talk, we summarise the construction progress of our facility, and the role that agile software development and open-source collaboration, and in particular the development of our TANGO-based control system, is playing.