To me, it's a matter of common sense and good manners to let the HC make their announcement first. It's what Michelle expected for herself when she's had her own significant life events. I know people will have different opinions about whether this is an etiquette violation, and it's good to hear them.
yes. This is how I see it. Unless you're specifically told, its not your news to share until those involved do, or give the go-ahead to do so. Plain and simple. I think its thoughtless and at the same time, a bit selfish. I have a friend who loves to take photos, and will post from events, like showers, weddings and so on, before those involved do. While its none of my beeswax, I always can't help but think maybe she should have waited.
and in her case, she is one of my best friends, and one of the nicest people I know, so in her case its really just cluelessness and not thinking since she doens't care if others do it for her events.