Sturridge's main injury had been misdiagnosed for 2 years (God only knows how!). Finally had corrective surgery in the summer, lad hasn't had a proper preseason in years and never had a chance to train without having pressure of coming back early.
I think Klopp is doing the right thing - no rush, no pressure. He's not given the media any indication of when he could be back or if there are any problems. Seems to me that he wants Sturridge to train and condition his body properly, without having a the pressures of a 'deadline'.
Having said that, there will come a time when people do lose patience - but for now, the major injuries have now been corrected and we will see if that plus the mini preseason will pay off.