It will take time to improve nurse-to-patient ratios in NSW hospitals, the government concedes, as it sets up an advisory panel of health leaders to deliver a key election promise.

The rule of one nurse for every three patients will be first enforced in emergency departments before the panel analyses the needs of other wards to determine what staffing levels are imposed around the state.

The group will advise on the speed of the rollout, with Health Minister Ryan Park hoping to achieve it in the government's first term.

"It will take time and but we have to start in our emergency departments," Mr Park said on Thursday.

"We believe emergency departments are the best place to start the reform because in a lot of ways, they're the front door for the public to our hospitals and they have been hit arguably the hardest in terms of over the last few years of challenges that the pandemic has brought with us."

The long lead time was "partly" explained by Labor's separate commitment to hiring 1200 new nurses and midwives by 2027, Premier Chris Minns said.

But more pressing was the need to slow the departure of staff, which the premier hoped would occur once the panel's advice was put into place.

"That's got to be the No.1 priority," he said.

"It's a lot easier to hold onto the talented, experienced, trained officials that we already have in our NSW health system than trying to replace that experience in the open market."

NSW nurses held high-profile rallies and protests in recent months to call for enforced nurse-to-patient ratios and argue the system had left them burnt out.

Under current settings, the number of nurses is calculated by care hours per patient day, which the union has long argued was failing to deliver safe supervision to patients.

The seven-member working group takes in high-ranking members of NSW Health and the state's nursing union and will convert hospital staffing requirements into minimum, enforceable standards.

NSW Health people and culture secretary Phil Minns, who is the premier's uncle, and NSW Nurses and Midwives Association general secretary Shaye Candish are among those on the panel.

It will meet regularly with NSW Health secretary Susan Pearce, who will update Mr Park on the group's progress.

Ms Candish said she believed the policy delivered on the union's ratio claim but some specialties were missing out.

"We've told the government there is much more to be done from that aspect," she said.

The union was committed to creating "real change" for nurses and patients, after years of the system "frankly ... exploiting" staff, she said.

A month ago the union filed a Supreme Court claim against the state alleging patients missed out on 100,000 hours of care in public hospitals.

The claim was rubbished by the Liberal health minister as "purely political".