Here is study of, of all things, "critical evaluation of information resources" by upper division undergraduates. Those who were seen as having crossed the threshold into their chosen professions, in some recognizable sense, were able to " . . . establish the authority, quality and credibility of [discipline-specific] information sources--a remarkable, if somewhat mystical experience.
Pronunciation change often happens as abruptly, with analogous parameters. The "authority" of a sound or word is best thought of as its place in the system or in those words where it occurs; the "quality" of the sound, its resonant and articulatory features; the "credibility," both the felt sense (haptic anchoring) and the confidence attributed to the changed sound or word. To the learner, a new pronunciation should, for the most part, just "show up," be a pleasant surprise, not be consciously integrated into spontaneous speech most of the time. For the instructor, the designer, the process and protocols must be transparent and managed. We haven't crossed that threshold yet, but we are closer.