I asked a question here previously related to this, and I would like to be more specific in this question. There are numerous ancient records such as the Ugaritic tablets, the Assyrian & Babylonian, the Amarna tablets and so forth. So what I would like to find out, is what known record contains the first appearance of this name, in any kind of variation (Misri, Musri, Masri, Msrm etc.)
For instance, the Amarna tablets have correspondences from 1300 B.C., and they contain Misri. So basically the oldest ones we have, would be considered the first. I don't have all the texts or knowledge at hand so it would take quite some time for me to find out this by myself. Thanks for the help.