Possible Clues:

• Prankster's time
• Time for tricks
• April 1
• Apt time for pranksters to do the starts of 17-, 22-, 50-, and 57-Across?
• Apr 1
• March past then this
• What's the anagrammatic reason for these odd questions?
• March past and then this
• Practical joke occasion
• Surplus explained at 113-Across