Final answer:
The briefing with the flight attendant crew conducted by the Purser or Flight Leader must take place prior to pushback. This is crucial for the crew to be prepared for their responsibilities throughout the flight.
Step-by-step explanation:
The Purser or Flight Leader (FL) is responsible for conducting a briefing with the flight attendant crew to ensure everyone is aware of their duties and any specific details for the upcoming flight. This briefing should take place prior to pushback to allow attendants to review safety procedures, special passenger needs, and any other pertinent information before the aircraft leaves the gate. Conducting the briefing before pushback is imperative because it provides flight attendants with the necessary information needed to assist passengers effectively, manage duties during flight, and respond to any emergencies that may arise.