The 32-year-old scored 10 goals and provided 31 assists as City won the treble last season, adding the FA Cup and Champions League to a fifth Premier League crown in six years.
De Bruyne revealed that he was carrying a hamstring injury for the last two months of the campaign and was forced off just 36 minutes into the 1-0 win over Inter Milan in June.
His first action back was off the bench as a second-half substitute in Sunday’s Community Shield meeting with Arsenal – where he set up Cole Palmer for the opening goal but then missed the first penalty as the Gunners won a shoot-out 4-1.
“I’m way ahead of schedule,” he said after the Wembley clash.
“I was probably looking to be back around the game vs Seville (in the Super Cup on August 16). I just enjoyed my summer, worked on my injury.
“I came back and the scan was good so I trained mostly alone in Japan. That went well, I’m happy.
“You don’t know how the injury will be. Mostly in the past I’ve always been quite a quick healer. It’s the body.”
City begin the defence of their league title with a trip to Sky Bet Championship winners Burnley on Friday night.
De Bruyne, though, admits he does not know if he will be fit enough to start at Turf Moor.
“I don’t know how I am physically,” added the Belgium international.
“I’ve probably trained five or six times with the team. I’m not too worried about it. I played 45 minutes at a good level so I’m happy with that.
“I’m getting better and there’s still around 70-80 games this year so I should be fine!”
Pep Guardiola has yet to confirm who will take over as City’s new captain this season after Ilkay Gundogan departed for Barcelona.
Kyle Walker – linked with a move to Bayern Munich this summer – led City out at Wembley, while De Bruyne took the armband when he replaced Mateo Kovacic on 64 minutes.
Asked about the captaincy, De Bruyne replied: “Nothing yet. I don’t know.
“If I get it, I get it. It’s not going to change anything I do for the club. This is my ninth year, I know the club inside out and people know whatever they ask of me, I’ll do.
“I’m not too worried. I try to do the same as always. It’s an honour if I get it and if not, it doesn’t matter.”