The young Celtic man is determined to make up for lost time.
The 20-year-old defender endured an injury-ravaged first season at Parkhead following a summer move from Manchester United, making just 13 appearances after suffering ankle ligament damage.
He arrived at Paradise with a big reputation but Celtic fans saw very little of him by virtue of his injury woes, but that could all change this season as the right-back looks set to make up for lost time.
Now fully fit, the Swiss youngster is gearing up to start the Hoops' Champions League second leg qualifier with Lincoln Red Imps tomorrow, after playing the full 90 minutes in last week's demoralising 1-0 defeat in Gibraltar.
But Janko has opened up on the 'devastation' which ruined his first season at Celtic, and pays tribute to team-mates Dedryck Boyata and Nadir Ciftci for helping him through the struggles.
“In training I got kicked and some of the ligaments went in my ankle. I was out for five months but they said it would heal naturally in eight to 12 weeks," he said to The Glasgow Evening Times. "It didn’t, I had to have the operation and I was out again for eight to 12 weeks. That was the problem.
“I was devastated. I was doing well. I got a few starts and I was also doing well with the national team. It was very frustrating but it is good to be back.
“Everybody helped. Celtic is a big family and everyone is supportive, especially the foreign players like Dedryck Boyata, Nadir Ciftci and whoever else helped me through it."
Janko, a former captain of Manchester United's reserve team, clearly has a lot of talent, and supporters will be hoping to verify that by the end of this season.