Well, I haven't fished Pittwater, but I have been up to Avoca off the rocks quite a few times. Up there, you just have to be there at the right time. Early morning is best, right after the sunrise. Sometimes you will get lucky, sometimes there won't be a single King. It's a little bit of luck off the rocks. Live yellowtail works well. If there are no baitfish, chances are there are no kings! If the yakkas are hard to catch (because of all the rubbish fish), try a whole garfish on gangs. The advantage of this is that you can fish any depth, not just several feet under a bobby cork. Huge casts aren't always necessary. All fish love structure, and the largest structure out there is the rock platform itself!
Sometimes you can do everything right and there won't be anything to show for it. But persistance pays off. I've been waiting all winter to get back up to Avoca and have another crack at the Kingies! Even if you don't catch any, the morning sunrise off the rocks is something to savour!