When I was up there a couple of winters ago I sailed from Illawong and there were a few kiters out but no windsurfers. It was when everyone else should be at work though.
Don't do what I did and sail over the rocks at the entrance to the river. I didn't realise how big they were and how they go all the way along the entrance. I broke a fin off (luckily I had another one in the board!). Later I took a walk out there to see if I could find it (I did) but I was surprised that the rocks were more like boulders.
I think the mistake I made was that the tide was going out and it started to get a bit shallow on some runs. It is amazing how the sand flats are so deep and as it was it was a bit of a walk back to the car from where I got back to the beach.
I also stuffed up and when sailing back to where I launched from I had no idea which beach was which

Next time I will take a flag!
As Bluedog says, it sounds like Salonika is much less tide affected.
I hate to say this, but I think if I lived up there I would take up kiting...