Possible Clues:

• Sixtieth day of the year, periodically
• The 29th, every so often
• Traditionally, when women were allowed to propose marriage
• A quiet delay—comes round every fourth year!
• Forthcoming opportunity for propositioning females?
• Intercalary event
• Time for a jumper in February?
• March sometimes delayed by one parking in van? Yes!
• 2/29
• 24-hour period occurring every fourth year