If one believes CASA's Flight Instructor Manual one would believe that the recovery method from an incipient spin is different from a fully developed spin. Identify when one is no longer in an incipient spin and suddenly the recovery action is different. See my extract from Cessna's Spin Booklet above, repeated here:
"During this incipient phase, spin recoveries in those airplanes approved for intentional spins are usually rapid, and, in some airplanes, may occur merely by relaxing the pro-spin rudder and elevator deflections. However, positive spin recovery control inputs should be used regardless of the phase of the spin during which recovery is initiated."
The test pilots and engineers who write the bits ablout spinning in flight manuals follow FAA AC 23-8C FLIGHT TEST GUIDE FOR CERTIFICATION OF PART 23 AIRPLANES which defines the spin:
No mention of the word "incipient" at all in that document.
When the word "spin" or "spinning" is used in the AFM or POH then it simply means "a sustained autorotation" and use the method in that AFM/POH for spin recovery.
That is especially important for types not approved for intentional spinning as they have only been tested for recoveries from a spin of up to one turn.
Picking up that Cessna statement again: "During this incipient phase, spin recoveries in those airplanes approved for intentional spins are usually rapid, and, in some airplanes, may occur merely by relaxing the pro-spin rudder and elevator deflections." "may occur" ... well, of course, the spin behaviour is changing all throughout the incipient spin phase so don't expect that to work at the instant just prior to the established fully developed spin.
However, it is a good technique for aerobatic pilots, in a type approved for intentional spins, at the onset of autorotation to centralise the controls and close the throttle.