https://www.guildwars2.com/en/news/a-guide-to-flame-frost-retribution/ says that when you log in, you’ll get an email telling you where to go.
•When you log in to Guild Wars 2, you’ll receive a mail updating you on the situation in the Shiverpeaks.
I’d logged in with an alt after the patch and then logged in with my main (didn’t check my alt’s mail). Couldn’t find the email on my main. Turns out, the alt got it; the first mailbox you log in with (even if that character hasn’t done any of the F&F storyline) gets the email and not the other(s).
This is at odds with the previous mails, where every character I have got a copy of the mails regarding the new living story. This time, only the first character to log in got the mail.
This is a bit confusing, and I’d recommend a note somewhere letting people know that. A patch is probably unrealistic considering the short time frame