How far to extend rain gutter?

I completed the new paint job and I'm re-installing the hinge and putting on a new rain gutter. My last rain gutter was a length of vinyl siding ripped from the bottom edge of a panel. It hung over about a half inch and worked well but after five years had shrunk and expanded so much it was pulling away from the roof.
I'm going with some 1/2" aluminum angle this time. How far should I extend the angle beyond the wall? Is 1/2" a common overhang? I have an 8' peice so no shortage of length for my five wide.

I'm going with some 1/2" aluminum angle this time. How far should I extend the angle beyond the wall? Is 1/2" a common overhang? I have an 8' peice so no shortage of length for my five wide.