After clearing with that first character do I need to log out inside the instance before I log on to the boss-killing character to accept the invite? Or does it not matter where I log out?The key to any lockout saving is to not kill any bosses on heroic. ICC is perfect because you can do every boss upto & including Sindigrosa on 10/25n, invite your alt, and then just swap to heroic inside.
This is the guide I used (shamelessly stolen from Wowhead comments).
Just, and I can't stress it enough, do not clear/kill a single boss on heroic. You'll fuck your save up.
Also, do I need to go all the way back to the instance when I want to invite a second boss-killing character?