waiting for zoro to master ACoC and start flying like oden, that mill most likely happen in act 4 though
if luffy needed two weeks to master the technique from scratch, zoro will take a lot less than that (a week) giving the fact that he already knows the basic of ryou flow
CoC is nothing if you can't control it, when zoro masters it and start imbuing his attacks with it he would be the only samurai in wano that's capable of actually killing kaido