go ahead vs pull back

go ahead

verb
  • To proceed with; to begin. 

  • Used to grant permission for or to give endorsement of a suggestion or proposal. 

  • To send communication over the radio. 

pull back

verb
  • To retreat. 

  • To pass (the ball) into a position further from the attacking goal line. 

  • Used other than figuratively or idiomatically: see pull, back. 

  • To score when the team is losing. 

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