Former Celtic manager Neil Lennon is in charge of Bolton at the moment, and Janko is delighted to have worked with him.
“Then in the second season I went to Bolton on loan,” the 19-year-old told The Scottish Sun.
“That was a great experience to play first team football in the Championship, which is a good league, and work for a good coach like Neil Lennon.”
Janko, who has joined Celtic from United on a four-year deal, will now hope to make an instant impact at Celtic Park.
The 19-year-old will have a lot of work to do to break into Ronny Deila’s team, but he certainly has the talent and the hunger to do so.
Celtic boss Deila showed last season that he is open to giving young players chances, and Janko will hope to impress the Norwegian during pre-season.
Janko’s versatility will also be a boon to him. The youngster can play both as a right-back and as a right-winger.