Now there's an argument I had with the late, great Darrol Stinton a few times. What is incipient?
Darrol used to reckon it was about the first 6 turns, and instrumented data I've been through from flight tests tends to agree with him - but the convention I am using here is that it is the phase between initial loss of control and the spin mode (e.g. erect to the left) becoming clear to the pilot.
G