The pair's current deals will expire in January.
"It is important that they know where they are going to be," Derry told BBC Radio Nottingham.
"We've begun talks, so the ball is rolling. If we can sort it out quickly it would be great for all concerned.
"Forget about Notts County and me - I remember as a young player just wanting to know where I was going to be. And I think that is key for them as well."
McGregor and Grealish both scored in Notts's 3-1 win over Gillingham last Saturday.