Pharmacy Next Day

Can anyone please explain from what date does the 7 year time closck start for neg account to drop off my Credit Servicereport? is is the last time you were late? what happens if your late here and there, when does 7 years start? How does charge offs figure into this date? Does each cra utilize a different date or is it all the same? How do deletion dates of collection agency(jdb) figure into this? Or can we all just make it up..LOL..