I think I asked the same question a few months ago and the answer I got was: DOFD is the first missed payment that lead to the delinquency that resulted in the CA or CO action. That is, the date from which you did not return to an "ok" status.
Others will chime in, I'm sure.
atlast....waiting on the mail
Ficos 2/17/08: TU 551 EQ 534 EX 587
Ficos 2/12/09 TU 695 EQ 715 EX 715
Fico...4/15/10....drumroll.....EQ 743