When you go to the market in Elis, there is a new stall in the top left of the map. Wait until the 1st day of the month and the vendor will appear and he will disappear after the 3rd day of that month. Be aware that this character seems to be designed to have their quests drug out over a month or two of game time. Unless you are going to cheat the date back and forth to go through his content, don't expect too much.
I haven't completed anything but his first quest, since it took me 2 days to build up enough relationship with him to resolve it and the second quest needed an item that I had to wait 3 days before I could retrieve it, so, doofus was long gone and ain't coming back for another month of game time. If I ever think about it, I might come back to try and finish his quests, but twiddling my fingers for a month, just to see the next quest does not excite me.