The site opens at 9am, and according to the OPW, it's another site that gets extremely busy this time of year, therefore I would imagine the earlier the better.
Our meeting time will probably depend on how long it will take everyone to get there? It's about two hours from here, so I'll go along with what suits everyone else.
Btw I did ring ahead, and as usual with OPW sites there are no restrictions on the use of tripods etc. providing it's not for professional purposes.