how long does it take for npcs to show up in terraria?

Answer 1

once they have a safe house for them yous till need to do a few things before each will spawn

like a nurse you have to increase your max health, for a merchant you must be carrying at least 50 silver

after thats done aswell it should be under 10 mins, any more than that you may need to reload the world

also note spawning the demo guy for me can be a bit buggy,