Of course it's been "done before"
It's still more of a thing to use here and there rather than a substitute for the regular jab, imo
[EDIT] - I may have misunderstood you.
If you put your shoulder "in" at the end of the jab (causing the elbow to flare some) it's too late for them to see it, it doesn't really add any telegraph because by then they're already getting hit and it can have more impact. That's might be fine if that's the case. Turning the fist at the end ALSO causes elbow flare (a little at the end) but too late to be seen.
If you're putting your shoulder "in" flaring your elbow at the beginning of the punch, then they can much more easily see what's going on and slip and counter you.