The Scottish international completed his return to Ibrox during the transfer window after finding that life South of the border with Rovers was not as he had imagined.
Ferguson will now be set to participate in his first Old Firm derby game since returning to Glasgow and he says that the comparison between the two local derbies is massive.
"They had told me at Blackburn that this was it - this was the game that meant everything. Bolton Wanderers at the Reebok Stadium on December 28, this was the derby Rovers wanted to win more than any other game.
"There were 27,038 there that day and I have to be brutally honest now and say that when I looked around that's when home and Rangers really started tugging at me.
"I respected what the game meant to Blackburn and the fans but I looked around myself and knew I was in the wrong place.
"I thought of my derby (the Old Firm match), the one that meant everything to me.And I knew then that Bolton-Blackburn just wasn't my place, I was brought up to dream of representing Rangers against Celtic.
"On Sunday I'll be in the middle of one of the biggest games in the world - I don't think you can argue with that."