Until Hillel and Shamai, there was ONE machlokes in Torah. Period. (about semichah).
And Froggie did quote THE pasuk in regard to learning, the one from where we see its a chiyuv every (available) moment, at the very beginning of Nach.
And why exactly are you not accepting of Chazal’s interpretations of the pseukim ?
A question is fine. The provocative “when did this mitzvah start”, applied to this clear and well discussed mitzvah, is not.
Methinks the issue in Emunah we have here is not the result of this question…
And that we should educate ourselves a bit before asking grand sweeping questions of such nature.