“I believe it will happen when they get in the ring. We’ve still got a way to go. But everybody is on the same page to make this work.
“We are all collectively working to get a venue sorted now.”
The bout will be the first time that the WBA, WBO, IBF and WBC heavyweight titles have all been on the line in the same fight.
“It is the biggest fight ever in British boxing, bar none,” Warren added.