The atlas's own cited source gives no single origin year for delegation as a management principle. The only dated instance is the Harzburg Model taught in Germany from 1956 onward, which is one documented application, not evidence of the principle's own origin.
What would resolve this A management-history source tracing delegation's own emergence as a formalized principle of organizational theory, distinct from any one later training program that adopted it.
OpenManagement historyWikipedia, Delegation