It's the opening ceremony. The opening of the tournament, that has already opened.
Why not have an opening ceremony each time a stadium hosts it's first game? Or each time a team first plays. The individuals involved will have subject to their own costs and complicated planning.
Just my opinion. Happy to disagree. I missed last night's opening ceremony (I was watching ITV on mute during the build up, no idea if it was shown on the red button or something but they didn't seem to show much other than some flag waving just before kick off). I won't lose too much sleep if I miss the other ceremonies too.