26 Jan is Australia Day which celebrates the arrival of the First Fleet and the founding of British settlement in 1788.
That might have something to do with the timing.
They had originally planned to do it in December, until they heard how many people would be likely to show up. Then they needed to beef up their logistics planning!
Ah yes.....in 1998 I flew into Perth, dog tired after the trip from L.A. and got settled into my Swan River side view room at the Duxton.......enjoyed the hell out of the air show and fireworks. That whole show caught me totally by surprise; I thought maybe my Aussie business contacts were overestimating my importance...