Possible Clues:

• Pressure-packed period
• Critical period
• Do-or-die moment, or what you must do to this puzzle’s theme answers
• When to pull an all-nighter
• Period before a big deadline
• When a chocoholic is under pressure?
• Hectic pre-deadline period
• Tense pre-deadline period ... or when to eat the ends of 17-, 24-, 37- and 46-Across?
• Final of the biscuit-eating contest?
• Critical juncture