go-ahead vs seal of approval

go-ahead

noun
  • Approval, agreement, or instruction to begin or proceed. 

adj
  • Progressive; exerting leadership. 

  • Being a score which gives the scoring team or player the lead in the game. 

  • Dashing; energetic. 

seal of approval

noun
  • official approval; sanction 

How often have the words go-ahead and seal of approval occurred in a corpus of books? (source: Google Ngram Viewer )