The rollout of the national broadband network is expected to hit its half way point by the end of June, as it begins to spread into metropolitan areas.
NBN Co says construction is accelerating, but warns that connecting homes in capital cities will cause disruption.
The company expects to have reached 5.4 million homes and businesses by June 30, and nine million premises by June 2018, when the end of the rollout will be in sight.
"This will be a significant turning point as we aim to finish the build by 2020 and become the first fully-connected continent in the world," NBN chief executive Bill Morrow said.
"We have developed strong foundations, processes and systems, and this year we will be opening up the NBN network to new regions, including many metro areas for the first time."
More than 70 per cent of the NBN's rollout so far has taken place in regional and rural areas, and more construction will start in metropolitan areas in 2017.
That will include Sydney city and Campbelltown in NSW, Moonee Valley in Victoria, Brisbane and the Gold Coast in Queensland, Salisbury in South Australia, Fremantle in Western Australia, and Hobart in Tasmania.
Access to existing infrastructure will be more difficult in metro areas, and there will be disruption for residents, but the payoff will be worth it, Mr Morrow said.