When do our facial bones stop growing?

Never: Although typically cranio-facial growth is complete in late teens for females and early twentys for males, or skeletal system continues to change throughout our lifetime. As an adult we have a whole new skeleton every 7-8 years. Bone changes to support our bodies against the effects of gravity and use.

18 to 22: Depends, but usual is 18 to 22, or so. When you stop having to buy larger shoes, it usually means you (and your facial bones) are fully grown.