We attended last year. We went big with dinner in the castle beforehand. We loved it. My only regret is that the table we sat at was entirely Americans... (not judging, but I get enough of us at home!)
Anyway I get their emails and you can start buying tickets. If you're planning:
https://www.edintattoo.co.uk/tickets-2023/hospitality-packages-2023/the-cannonball
It was well worth the money we spent for the entertainment we got.