Near the beginning of the film, Wendy is telling the doctor about Danny. She tells her that Jack dislocated Danny's shoulder when he pulled Danny away from his school papers on the floor. Wendy says that after the incident, Jack promised to quit drinking or Wendy could leave him. She said Jack hasn't had a drink in 5 months.
Later on in the movie, Jack is telling the same story to the bartender. But he said it was three years ago.