Gomez, the top Bayern goalscorer in the past two seasons, has been replaced in the starting line-up by Mario Mandzukic who has already scored three goals in three league games so far.
"I do not know myself when I can fully use the ankle and train with the team again," the Germany international told Munich's tz newspaper. "I am impatient but I cannot estimate it. I do not know how far I am."
"It depends on each day. At the moment it is good. But don't think I spend an hour on the treadmill."
Gomez scored 26 league goals last season as well as 12 more in the Champions League with Bayern reaching the final but losing to Chelsea. He also netted three times in Germany's run to the Euro 2012 semi-finals in June.
Bayern are top of the Bundesliga and host Valencia on Wednesday in their Champions League Group F encounter.