The Argentine striker has been out since February after rupturing his cruciate ligaments in a Europa League match, ruling him out for at least seven months.
Milito has admitted that progress has been slow during pre-season, with the veteran forward now stepping up his rehabilitation in order to stay in the thoughts of new Inter boss Walter Mazzarri.
He told Gazzetta dello Sport: "The initial dream was to be there for maybe the beginning of the season, but today I really do not know when I could [return]. Of course, in mid-September there is a certain game [Inter-Juve] at the San Siro. However, I'd prefer not to delude myself anymore if I can [avoid it].
"I'd never had serious injuries before, and any injuries I had were always in my muscles, they do not compare with that pain. From the outside you suffer too, and want to lend a hand without being able to do so. It is a feeling that hits you in the stomach. There is always something you want to try and give, regardless of injury.
"I speak often with the doctors, but we have not set a date on the calendar. I go day by day. We are on the right track, let's say at the stage of finishing, but with a duty not to risk anything. It's not worth ruining the good work: at these levels nobody gives you anything. And I'm still missing something: the rhythm, match practice and so on."
The 34-year-old has scored 73 goals in 152 appearances for Inter, including a brace in the 2010 Champions League final.