I don't want to say too much about it, they're obviously waiting to tell people for a reason, but I got the invite to mine on Tuesday, replied straight away and got the email with further details on Thursday. It's at the end of next week, so they'll maybe wait to send info to those with later AC dates?
As for the tasks, they sound intimidating for someone like me who's never done an AC before but they're pretty standard. It's not a long day either.