Gannon told BBC Look East: "I think it's important that I make the situation clear so we can start planning for next season.
"Maybe by the end of the week it will be a prudent time to make a decision."
Posh are keen to have Gannon on board for next season regardless of which league the club find themselves.
He currently has a contract until the summer, but is happy with the extended terms he has been offered at London Road.
I feel sure that if he was staying he would have let MacAnthony know by now
ExFleet
"I had a second opportunity to sit down with the family this weekend and reflect," he said.
"You have to sleep on things and chat them over and it's a very difficult decision either way."
Ahead of their trip to Scunthorpe on Tuesday evening, Gannon will once again be without a number of key players.
Aaron Mclean is set to undergo knee surgery on Thursday and will be ruled out for the rest of the season, while Craig Morgan also has a knee problem.
Lee Frecklington (calf), Sergio Torres (dead leg) and Liam Dickinson (hamstring) are major doubts, while Ryan Bennett (ankle) and Izale Mcleod (knee) are long term injury concerns.
"Ryan has been out for several weeks and will require extensive rehab once he returns to training, but he could be ready for selection in a couple of weeks," Gannon said.
"Izale is effectively out for the season so we're discounting him unless we here otherwise from [parent club] Charlton."
Posh are ten points from safety following Saturday's defeat to Nottingham Forest with eight games remaining.
Gannon knows they are nearly relegated, but says there is plenty still left to achieve this season.
"We needed a few things to go for us over the last couple of games and unfortunately they haven't," he said.
"But I don't just want credibility now, I want the players to come away with some brilliant experiences to take into next season."
Source: BBC Sport
Source: BBC Sport