Tyson Fury v Dillian Whyte is unlikely to happen in March with the purse bids now set for Friday, according to Eddie Hearn.
Mandatory challenger Whyte has been unable to agree to terms with Fury after the WBC ordered an 80/20 purse split in favour of the reigning champion.
Speaking to the 5 Live Boxing podcast, Hearn said: "People keep talking about March dates - that's starting to look unrealistic for a fight of this magnitude."
Fury's co-promoter Frank Warren told BBC Sport last week that the targeted date was 26 March, but Hearn says April is far more likely.
"Either March, April, early May potentially," added Hearn. "This is the window for the fight. Depends what happens this week.
"There are so many conversations going on behind the scenes right now. Something could turn at any moment."
Whyte, 33, is currently in a dispute with the sanctioning body WBC after their purse-split announcement and also the time it took for the British heavyweight to receive his shot at the world title.
Hearn, who works with Whyte, says despite the disagreements between the two camps and the WBC, the fight will still go ahead.
"You're talking about a lot of money - a difference of 25%," Hearn said about the issue.
"The normal split for any mandatory challenger is a lot more than 80/20. The normal split for an interim champion is up to 45%. We feel in terms of the commercial value of Dillian Whyte and the time he's had to wait, 80/20 is quite ridiculous really."
He added: "[It] looks like Dillian Whyte will definitely get his shot at the WBC title, but we have to fight for his rights and make sure it's fair. It's not going to stand in the way of the fight."