I spoke with Kilton on the western eye island of the Skull Lake. Later I was actively looking for him and I teleported to Hateno, and found him where he's said to be, according to this seemingly complete guide.
Now I want to find the store again so I stalked his Hateno spot for 20 nights by sleeping in my home until morning, then until noon, then until night, then at night go to his spot and back to my home. But it didn't work.
Another guide on the Internet mentioned there'd be a sign if he'd appear at one spot at night. So I tried all of other locations, in a single in-game day to find that sign or the shop. But there was nothing.
I thought maybe I loaded a previous save where I haven't spoken to Kilton or started the quest, but no: everything is fine on that level.
So how can I find the Fang and Bone reliably?
Best Answer
The Fang and Bone appears outside every major settlement between 9pm and 5am (except Goron City) in the same spot every night.
It's fairly easy to locate, simply by finding a vantage point and scanning the surrounding area.
Source
It is important to note that he will only appear when you show up in an area after the time that he is meant to show up. He will not simply materialize in front of you when the clock strikes 2100. Your best bet is to wait until 2130-2200, and approach the area/teleport to the location then, but you can re-teleport to the same spot to re-load the area (I have personally tested this).
Alternatively, people have suggested locating him under the Bridge near Tarrey Town, which seems to "reset" his cycle.