If done properly it should not take more than a few days to feel a great relieve and changes. When Black Magic is destroy it happens instantly after the moment the magical operation is perform, yet the person may take some days to feel the changes. I have seen people that is sensitive to spiritual energies to feel it the next day. Most of the people offering to help others in cases of Black magic had no idea what they are doing, and are just after the $50 dollars or plus the charge. Real Black Magic removal take a lot of skill and years of training the mind in meditation, developing the inner senses and imagination. Also natural magical talents and to have reach Enlightenment to be able to really see behind the veils of illusion and truly destroy the source to the black magic.
So if you were told months your were lied to plain and simple.
God Bless you,