IF I choose to give a standing O, it could be at any time. If I was utterly moved by the enitre production, I will stand right at the begining of the CC.
If I loved the show, but thought that a specific actor is what amazed me the most or really stood out amongst the others, I'll stand when that person takes their bow.
I will not stand "just" because someone in front of me blocks my way, even though its annoying that I can't see. If I don't feel that the show was outstanding, I will politely applaud (at whatever level I feel appropriate) from my seat.
There is no right or wrong or protocol.
If we're not having fun, then why are we doing it?
These are DISCUSSION boards, not mutual admiration boards. Discussion only occurs when we are willing to hear what others are thinking, regardless of whether it is alignment to our own thoughts.