Between the link and icon. If it has an arrow next to it (iOS loves triangles and GT/LTs), to indicate it goes somewhere, etc. Does not include add-ons (off site icon) if a link. This is for the special case where THIS is the indicator (get it) that there's something the associated text does.
Usually horizontally aligned. Left or right of the text. Yes, reveal items and leaf node icons in the reveal list are this. Others maybe, so go find them.
Good one: Using icons for content type, whether PDF icon or an avatar image, is a type of this... Make this make sense with the list style that describes it already.
NEVER just put text down without link styling or an indicator!