To the best of my knowledge, I don't recall anyone official stating when they expected him back. Regarding the injury, I'm no doctor, but I had a similar injury in high school. Sano has a 'stress reaction' in his shin. Mine was never officially diagnosed, because X-Ray didn't reveal anything, but that's kind of the point of a stress reaction: It's a precursor to a bone fracture, that can't be observed because it's too small. It can be in the muscle near the bone, in the bone tissue, or the bone itself. It needs to heal 'enough' so that it doesn't get worse when he performs baseball activities (which he's not there yet). But, considering you can't see it in the first place, the only thing to do is give it time and keep testing it. He keeps reporting soreness after activities, so his is not healed enough yet. Honestly at this point I hope the Twins can clinch the Wild Card spot and have a game or two to give Sano a chance to work on his timing during worthless at bats, before the Wild Card game. You can expect that if he plays again this year, it will be at DH only and not at third base.