Hugo Gernsback launched Amazing Stories in April 1926. This was a big deal for “scientifiction” as Hugo called it. An all-Science Fiction magazine! This would be a logical place to begin looking at Pulp robots. But even during the Pulp era, there were precursors to Amazing.
One magazine that set the stage for what was to follow was Weird Tales, edited by Farnsworth Wright (1888-1940), it was not an all-Science Fiction magazine, typically regarded as a horror magazine. But as editorial assistant, Otis Adelbert Kline, wrote in an early editorial, “Why Weird Tales?”, “The Unique Magazine” published three kinds of fiction: horror, fantasy and what:
…. might be termed “highly imaginative stories.” These are stories of advancement in the sciences and the arts to which the generation of the writer who creates them has not attained. All writers of such stories are prophets, and in the years to come, many of these prophecies will come true.
If you’d like to read the rest, please check out Monster 2: From the Pages of Dark Worlds Quarterly.