having said that vs if only

having said that

conj
  • however; despite what one has just stated 

if only

conj
  • Even if for no other reason than; only just. 

  • Used other than figuratively or idiomatically: see if, only. 

  • I wish that; signifies a wish or desire for the present or the future. 

  • I wish that; signifies a regret about an action in the past. 

How often have the words having said that and if only occurred in a corpus of books? (source: Google Ngram Viewer )