Was the first implementation of looping control flow effectively the goto  (or something like a labelled JMP in assembler) or was there another syntactic construction?for (fr) was introduced in Superplan in 1949 IIRC.
Did labelled loops pre-date for loops?
history;loops;control structures
I'm not sure if your question title matches the actual question, as jump instructions in assembler may be relative, i.e. unlabelled as well. I'm also no historian, but I can at least subtract another century from your estimate.The Analytical Engine devised by Charles Baggage in 1837 was extended in 1845 to contain a conditional jump instruction similar to modern assembler jump operations. See the linked wikipedia entry for an example code.While that sets back the first implementation of such a control structure by a good century, I cannot say whether earlier versions exist. Most probably you may need to refine your question, as I believe there exists earlier work on the theoretical concept and it's hard to decide whether anything before the analytical engine is an implementation depending on your definition of it.