Interesting Times

If you are having trouble finding this NPC you need to do the BFA intro quests. As soon as you tp to the new faction main city you will be able to see the NPC in SW. Had trouble finding the him on an alt, but did the quests for BFA and he is now there.

The quests you get for the neck etc.

See dasbaum's comment on the horde version for even more information.

Edit: Did not have to do this on my 107 warlock or 34 warrior. So I am guessing that it's a 110 issue, or maybe it because you are in the middle of the intro quests. I had Attend War council q and speak with Jaina left to complete.

Edit 2: Lvl 110 char that had not started the BFA quests did not have to complete it to see the NPC. Ergo: If you have started the BFA intro quests, finish them.

A Chinese curse and/or a Discworld reference:
“There is a curse. They say: May you live in interesting times.”, Terry Pratchett, Interesting Times

Do you only get the "Slightly More Urgent letter from the Timewalkers" on only one of your characters? Because I have logged in on multiple characters and it was only the first one who got that letter.

Edit: After scrolling down and reading Ledning's post, I logged onto a toon who had not done the BfA intro quests but whom I had logged onto earlier and received the 14th Anniversary package, but not the letter. After doing the intro quests up to getting all set up in Boralus, I went back to SW and in the library I found the NPC, who gave me both quests without my having received or responded to the letter.