In this video I explain what I was taught in terms of a Harmonic pattern "working". In this example I initially look at a BAT pattern and I walk you through what it means for it to "work" and later on I show the same for a GARTLEY pattern.
In essence when price turns at D, you can consider the pattern having worked once price passes A. You can take profit or even exit the trade before that, but that has more to do with an individuals trade management, in this case I am specifically focusing on what I understand as a Harmonic pattern "working".
Hope this helps.