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?