As you have been cleared to carry out a instrument approach procedure you must fly that, unless you negotiate something different with ATC. The concept of an instrument approach is to put you in a position whereby you can land visually. Unless this is a Cat3B No DH approach, you must at some point gain visual references in order to land. If you understand this logic is follows fairly simply that you must fly to the FAF, then when once visual you may adjust your flight path to conduct your visual landing.