The royal commission was set up by former Prime Minister Julia Gillard in 2012 with a massive budget of A$434 million (NZ$443 million) over four years.
Despite this, Justice McClellan said he did not have the resources to hold public hearings on 1000 institutions, but would select enough to cover all the kinds of institutions where child sexual abuse was alleged and all parts of Australia.
He is currently chairing hearings on the best way to provide redress to child sexual abuse survivors. His commission has proposed a national redress scheme backed by the federal and state governments, but Prime Minister Tony Abbott's federal government opposes the idea.
"Whether or not government will take up that redress I don't know, but I know all of the major institutions - church and beyond - have joined us in saying we would like there to be such a scheme," Justice McClellan said.
He said the commission was also working on rules that institutions could adopt to ensure that child sexual abuse did not happen.
"There are arguments about whether there should be a regulatory process provided by government or by voluntary arrangements that would provide that institutions will have to conform to the rules in the way they conduct themselves in order to be eligible for subsidies and government money, and to be able to 'market' their services, so to speak, to the general community," he said.
"They will be able to say, 'We have been audited and we meet child-safe obligations in the way we conduct our business and the way we run our facilities."
In New Zealand, last year's Vulnerable Children Act requires police checks on everyone who works with children in a state or state-funded agency from July 1 this year for new "core" workers, who sometimes work with children unsupervised, and from July next year for "non-core" workers who are always supervised.
All existing workers require the checks by July 2018 for core workers and a year later for non-core workers.
Police programme manager Alice Greer urged agencies at the conference not to request police checks for all 280,000 workers believed to be covered by the new law all at once.
"We vet 500,000 people a year. If we had 280,000 vulnerable children's workers come in the first year, we would break," she said.
"I strongly urge you to take the full three and four years that you have for your existing staff. That way we can provide you with a good service."