Just north of the benches in Prontera there's a Wizard, speak to him and he'll send you inside.
I do like the layout and when the dungeon warpers get moved I think it'll be pretty neat. After Janeway is implemented there I'll probably spend some time there on various guys looking for groups on my other dudes.
I'm not sure how much gear you want to put on the armor/weapon vendors, but you probably want level 1/2 weapons for every class and maybe armor types for most classes too (but not everything). If you end up putting one of everything in it's going to be a lot of choices which dont really need to be made. Do you think an upgrade npc would also be worth putting in near by?
Thank you. I finally found it under the vend shops. 
I love this idea. But may I suggest changing a few places for the NPCs?

I'd suggest moving the dungeon warpers below the steps leading to the castle. This frees up the area just north of the steps, where the first class guide NPCs can go with them standing side by side. Yeah, there will be people around that a novice can ask where to go, but these NPCs are the main reason for this Training Village, so they should be "front and centered". The area where the first class NPCs were can be used for other NPCs if you wish, like maybe a repair NPC (not necessarily just an NPC to repair gear, but could also teach newbies about items breaking, and how to avoid it, if you wish) or maybe Kafra shop NPCs or... it could be left empty...
And FYI, Primo d'Buffer gives agi up, even to non-VIPs. No need for an agi NPC (L).