Mayor of London Boris Johnson has confirmed that the Night Tube service will begin in July.
Speaking to the Press Association, Johnson said he had been given the approximate launch date by Transport for London.
The service was previously though to be starting in August.
Services will run through the night on Fridays and Saturdays on the Central, Piccadilly, Northern, Victoria and Jubilee lines.
When asked if the Night Tube would be ready to go in July, the mayor said: "Well, that's what I'm told by TfL - towards the end of July."
However, a TfL spokesperson was less confident. "We are working to deliver the Night Tube for London this summer. The earliest that we could introduce it would be late July. In the meantime we are recruiting and training the part-time drivers who will run the service when it launches later this year," he said.
When talking about the delay, Johnson added: "We've had to go a bit slower than I necessarily would have wanted, but on the other hand better to do that ... I thought Londoners would rather wait a little bit than we pay an exorbitant demand to get it done."
The hold-up was caused by a dispute between TfL and driver unions, however, the issues were finally resolved in recent weeks.
"We were always clear that we were in favour of Night Tube," said Finn Brennan, Aslef's London Underground organiser.
The 24-hour weekend service was due to launch in September 2015 but was derailed after Tube staff refused to accept the terms being put forward. London's commuters were thrown into chaos on several occasions because of strike action, as workers sought assurances that their "work-life balance" would be maintained, rejecting several pay deals in the process.