Those are a bit different from the OP’s examples. In your examples, numbers are used in place of letters; in the OP’s examples, a number, meant to represent a number, is inserted into the middle of a complete word. The former seems like it’s mainly a recent phenomenon; the latter, I don’t know.
Not as early as the other examples, and not exactly what the OP was looking for, but still neat: E5C4PE by Journey (1981) Cover art: Escape (Journey album) - Wikipedia
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That’s a cool collection of examples, but let me refine the question… Who was the first firefighter (or fire truck painter?) to come up with the idea of using ENG1INE instead of ENGINE 1?
Da5id, a character in Stephenson’s Snow Crash, 1992. The 5 in the middle is a replacement for the “v” usually found in David… the “v” being a Roman 5, so a number replacing a letter that is a number.