How soon must you request late fees from your tenant if they pay late? The contract doesn''t give a specific nbr of days you must request the late fee.

This is a land option deal. Contract reads "Buyer agrees to pay $50 penalty in the event any pmt is made more than 5 days after the 1st of the month". He never wanted receipts and we were nice and didn''t collect late fees when he paid late. Now he wants to close and we want to collect the late fees but the occurrances have happened randomly over the past 32 months.