How effective is saline removal of a tattoo and can it be done immediately?

Saline injection is not an effective method of tattoo removal. The risk of scarring is significantly higher than with tattooing, especially if you allow it to be done by a non-medical person who has already demonstrated a lack of skill in cosmetic procedures.
I recommend you do nothing for 8 weeks, and then see a physician about laser removal. This is the safest way to avoid doing irreparable harm to your face 
Good luck to you.