Government-owned network builder NBN Co has released detailed construction maps revealing where in the city the rollout of the network's fibre cables will begin.

The boundaries of the first two construction modules include parts of Market and Smith streets in the north, Wollongong Hospital and Gladstone Avenue in the west, and Bridge Street in the south.

MAP: The roll out of the National Broadband Network

The area includes an estimated 5000 to 6000 premises and covers the Wollongong CBD.

NBN Co expects homes and businesses will be able to access retail services via the NBN in about 12 months.

However, residents in North Wollongong and the city's northern suburbs will have a longer wait, with work to begin next year.

The company has released maps that it said covered a further 44,700 homes and businesses statewide.

In addition to central Wollongong, maps were released covering thousands of properties in and around Dapto, including Brownsville, Kanahooka and Koonawarra, where work was also expected be completed in late 2013.

NBN Co spokesman Darren Rudd said contractors would start testing existing Telstra infrastructure in the rollout areas.

He anticipated residents would start receiving offers from internet service providers in five to six months.

Meanwhile, NBN Co has announced that homes in 15 early rollout locations across Australia, including Kiama Downs, would have 18 months from November 23 to switch over before services using the old copper network were switched off.