How to unlock furniture shop ?
Hey man, it unlocks by playing through the story.
Quick and general progression would be:
Attend Paulina's lessons during the day-->Do the goblin elimination mission-->Then help Paulina out with a task. After that, you'll get to have a celebration, and the furniture shop should unlock afterward. There's a possibility you might need to do some stuff at the inn, but yeah. That's the general path.