When I was trying to get my act together back in 2018, I got current on a few cards and loans for a month or two, but then went late and eventually into default/CO on them. Eg: first missed payment sometime in 2017, 120 days+ late May 2018, current June-July 2018, first 30 day August 2018. I'm assuming the date of first delinquency will be August '18, but is this something a goodwill letter might help, to consider the earlier date? Or will I ultimately be punished for having one month of getting current and paying all those late fees? (I think I know the answer, but thought I'd ask anyway. 
Unfortunately a creditor wouldn't "move" the DOFD. It is set in stone by the first late that subsequently led to a CO. The CRAs determine this, not the creditors.
@RobertEG wrote:The date of first delinquency is not the date of any first deliinquency, it is defined under FCRA 605(c) as the date of first delinquency in the chain of delinquency that ultimately included the CO.
In the posted scenario, it would be 08/2018.
The DOFD is required, per FCRA 623(a)(5), to be separately and explicitly reported to the CRA. It is not interpreted or inferred by the CRA based on payment history profile.
It is not something that the creditor has any discretion to change or report other than its actual, factual date.
I stand corrected about the CRAs determining DOFD.