Indigo finishes Christmas Island->Perth
https://www.itnews.com.au/news/indigos-perth-singapore-cable-builders-lay-first-section-512795
ASC achieved that stage April 18
https://australiasingaporecable.com/articles/australia-singapore-cable-main-lay-progress
So we are 5 months ahead, and they are probably looking at mid Feb before Perth->Singapore could go live
When it gets to that stage, its probably only Telstra that have the backhaul from Perth to Sydney to shift data off SMW3, the other partners might wait until the Perth-Sydney section is complete 'mid 2019'.