It’s harvesting souls not corpses?
But you hit on a point there.
Time line.
1123 - Shaeönanra, Grandvizier of the Mangaecca, claims to have rediscovered a means of saving the souls of those damned by sorcery. Mangaecca was promptly outlawed for impiety. Mangaecca abandon Sauglish and flee to Golgotterath
2143 - In spring the No-God is summoned. Across the world, Sranc, Bashrag, and Wracu, all the obscene progeny of the Inchoroi, hearkened to his call. Sag-Marmau and the greater glory of Kûniüri are annihilated. All Men could sense his dread presence on the horizon, and all infants were born dead. The 11 years when all infants were still born comes to be known as the Years of the Crib. Anasûrimbor Celmomas II had little difficulty gathering support for his Second Ordeal. Nil’giccas and Celmomas were reconciled. Across Eärwa, hosts of Men began marching toward Kûniüri
So it took 1000 years, ish to summon the NG the first time.
And 2000 years have passed since.
Why would it take twice the time?