This was from Athol Bay during the Naval Fleet Review, October Long Weekend. We arrived about 8am and there was plenty of space. We anchored about half way between the shore and the exclusion markers. I guess about 90% of boats are out just for the day so getting out early will ensure a good spot easily. By lunchtime it was getting busy and new arrivals spent much longer finding sufficient space and lots of stuffing around resetting anchors.
Mid afternoon was too late and there was a little bit of angst about the bay with too little space for new arrivals or big cruisers arriving and blocking views. Be prepared to defend your turf and view late in the day.
If you go out early, don't find a spot with too much space around you as you don't know what kind of monster cruiser will plonk nearby. We deliberately anchored in behind some low rise boats to ensure our view would be maintained for the fireworks.