User blog comment:Black Leg Sanji/Where is Kaido?!/@comment-3060121-20120226155714

He is probably looking for OP like the rest of the world. Even though we saw the other yonkou we dont exactly know what they do with their time. So he's probably conquering islands and trying his best to find OP first. Or he may be Doflamingo's friend and until the time skip has been preparing for the New Age.