If you want more relevant citation then this: "A journey of a thousand miles begins with a single step" (C) Lao Tzu
For that matter I would say that first major step to real FOSS was made in 1917. But it was too early and shouldn't that brutally enforced. Evolution is the only reasonable way to get anywhere in such complex systems.
Relevant fact: all hardware and software in USSR was Open Source. Any non-trivial product must be and was accompanied by full schematics. Software sources must be printed out, etc. By law.