knuckle down vs move in

knuckle down

verb
  • To get to work; to focus on a task. 

  • To submit; knuckle under. 

move in

verb
  • To start living or working in a new place; to transport one's belongings to a new home or workplace; to make one's home or workplace into a suitable environment. 

How often have the words knuckle down and move in occurred in a corpus of books? (source: Google Ngram Viewer )