My debrief was given me straight after my PPL test. It consisted of me asking him "any problems". His response? "you'll be alright".
My instructor says they often talk to each other about students who have passed but have a few things that need an eye keeping on, and this info can filter back to said student that way. Outcome of such a discussion regarding myself? "He'll be alright"
From middle-aged South Yorkshiremen, volumes.
So in answer to the OP, I suspect any debrief should be offered straight away, although it might be as brief as three words!
I'll vacate this thread now.