The 25-year-old, who is currently recovering from a dislocated knee cap, is aiming to be fit in time for the game against Manchester United on September 10.
The German international, who recently joined City from Borussia Dortmund, told Sky Sports: "Our target is end of August, September and September 10 is the derby, so I could be ready for it, but it's difficult to say.
"If it's one week earlier it's good, but one week later is also good. The important thing is to be safe and then everything else will come on its own.
"Everything is going well and I am looking forward to being back on the field.
"I'm doing my rehab, increasing the pressure on my leg, and I'm in good shape and looking forward to it."