Disability Minister Joy Burch said on Wednesday older Canberrans, young children and school leavers would be among the first to change to the territory’s two-year NDIS trial.

After it starts on July 1, as many as 5000 people will take part in the NDIS trial in the ACT.

The phasing timetable was approved by the federal Assistant Minister for Social Services, Mitch Fifield.

“The ACT government has undertaken considerable analysis and research to develop a strategy for moving people into the NDIS in a way that is equitable, practical and efficient,” Ms Burch said.

“The ACT will be the first jurisdiction in Australia to accept all eligible people into the scheme and, obviously, not everyone will be able to access the NDIS on day one.”

Ms Burch said older Canberrans will switch first, helping as many as possible avoid the NDIS cut-off age of 65.

In the trial’s first year, 64 to 59-year-olds will transition, followed by 20 to 58-year-olds from July 2015.

Children under four will change before the end of the year, and high school and primary school-age children will transition next year.

Ms Burch said disability group home residents would transition separately, home by home, while young people with high and complex needs who left school between 2008 and 2013 would join the NDIS trial this year.

All 2014 school leavers will switch at the end of this year.

The National Disability Insurance Agency will open Canberra offices from July 1 on Northbourne Avenue in Braddon and at Nature Conservation House at Emu Bank, Belconnen.

The announcement came a day after the NDIS trial received a $5.1 million boost from the ACT budget, and during a conference considering the scheme's impact on mental health provision.

The policy and sector development manager at Mental Health Community Coalition of the ACT, Simon Viereck, said there had been significant concern and cynicism about the NDIS in the mental health sector.

“There has been a lot of concern around words such as permanent disability and how that would that fit with the cyclical nature of mental illness, how would it fit with the recovery approach,” he said.

“It is easy for people to be cynical – they’ve gone through a lot of reform that hasn’t delivered any better service in the end really, or didn’t deliver for them, so for them to trust that this reform will actually make a real difference to their lives, there’s some cynicism for us to overcome.”

The conference on Wednesday heard from mental health and disability expert Eddie Bartnik, who was Western Australia's first mental health commissioner. He has been engaged as a strategic adviser to the National Disability Insurance Agency.

Mental Health Community Coalition ACT executive officer Ian Rentsch said the conference was about starting the conversation about what the NDIS would mean for people and, in particular, those with a psychosocial disability.

“As one of our speakers pointed out, the mental health sphere came into the orbit of the scheme quite late and we’re still trying to catch up and understand for ourselves and consumers and carers what that really means for them in terms of support,” he said.

“The concerns have been about ... what a person with a mental illness, how they are going to be seen in the NDIS sphere.

“I think people are still thinking about what it’s really going to mean for them. For the agency itself, the challenges are ensuring that a person who comes in with an approved plan can actually get the full range and support of holistic services."