To foil Jacob's plans, the Man in Black takes the form of Kelvin, who's body must have somehow arrived on the Island (the original Kelvin having served in the Gulf War), and using his abilities, knows exactly when Desmond will wash ashore hence the reason he is already at the spot where he does and wearing the suit that he knows he doesn't even need. He takes Desmond back and waits a couple years until he knows that Oceanic Flight 815 will be flying overhead. He then makes it obvious to Desmond that there is a rip in his suit to get him to follow. He leads Desmond far enough away from the hatch that he won't be able to get back to it before it pulls the plane to the Island, evidenced by his failure to confront Desmond until he gets all the way to the cove.