How do I verify when negative items drop my credit report?

I understand that negative items remain on your Credit Report for 7 years after the date of Original Delinquency, but how do I determine when this date incurs? Since the "Date of Last Activity" changes extending the date of deletion on your credit report, how can I determine when items should drop off?

It is seven years after you pay off the debt, the month/year you paid if off appears on your credit report.