Pip back pay

I received a copy of my report today that states 13 points for care and 12 for mobility

My claim was first started 13th may but as I was suffering with real bad depression I didn’t return the forms.
I got a letter in August saying my claim had been refused due to not returning the form so I called in September and asked if I could still return my forms and I had a text saying about it being an MR. A few weeks later I got a letter saying
Thank you for returning your form, we have decided you had good reason for sending them late and we will now continue with your pip claim.

Does that mean if they award me pip will they backdate from may when I began the claim or from September when I returned the forms

Thank you

Pilly

Providing this was a new claim and not a transfer from DLA to PIP then the Decision will apply from the date that the DWP accepted your claim, this should be the day that you contacted them to start it.

Gordon