premise: John von Neumann's Universal Constructor is a self-replicating machine in a cellular automata (CA) environment. It was designed in the 1940s, without the use of a computer. The fundamental details of the machine were published in von Neumann's book "Theory of Self-Reproducing Automata", completed in 1966 by Arthur W. Burks after von Neumann's death.
hypothesis: John von Neumann's Universal Constructor was created in the early 20th century.
reason: Since John von Neumann's Universal Constructor was created in 1940s, then yes, it was created in the early 20th century.