Nelsen has been appointed head coach of Toronto FC and the Major League Soccer club expect him to start work on February 1, ensuring Tuesday's Barclays Premier League clash with Manchester City will be his final game for Rangers.
"I need to speak to Ryan, I need him here for the Norwich game," said Redknapp, who revealed Nelsen will be rested for Saturday's FA Cup tie against MK Dons.
"I thought we were talking March 1 when I spoke to Ryan last. Suddenly this has all changed. I'm hoping we can put it back a few days.
"He's been away all week in Canada doing some work for his new club. I need him next week - we're desperately short and I need Ryan to play.
"He's got a job to go to and wants to crack on with that. He felt it's an opportunity that may never come along for him again.
"I can understand where he's coming from because it's his future, but I wish he was staying because there haven't been too many better players than him here this year."