Redaction: When Mormon indicates that he will proceed to finish his record, he is referring to the return to the text that has already been written, not that he would begin to write the story of Benjamin. Consistent with his terminology, he indicates that the source of the abridgement is the "plates of Nephi." This interjection serves as part of the time-linking between the addition of the small plates in their chronological order and the understanding that a future reader would been to return to Mormon's account. Mormon's testimony to his personal relationship to the plates is understandable from Mormon the editor, to whom all of these historical records were in the "present tense" - that is, he had them present before him. While the documents deal with time depth, Mormon's "present" spans the whole work, and his frequent editorial insertions all indicated this type of "present" consciousness while he works with the historical material.
While there are internal reasons to use the "small plates of Nephi" designation or the plates Mormon has inserted, it is not one that Mormon used. Indeed, Mormon does not specifically name them, nor refer to them as anything other than "these plates." However, I have suggested that he might have introduced them by their duplicative "plates of Nephi" name in the putative lost introduction.