The Late Darrol Stinton, who I knew well and worked with maintained that the incipient stage was the first 5-6 turns, and there are good data to back him up.
Personally I think it's until the direction of the spin is clearly established. We had some good arguments about that.
Either way, we need some clear definitions that I don't think are currently in universal use.
I do not understand the justification for requiring spin or UPRT training in an integrated course, but not any other form of CPL course. It's the same licence and the same need.
G