Always later, start en media res. (idk if I spelled that right). Think of their origin story as a cause, and then jump strait to the effect. What is the end point of their origin. Like Batman's first night cleaning up Gotham, or maybe one his early nights, or even further on. You could have it be the first time they encounter the villain. Logically you could know this villain and the hero go way back (like villain killed their parents), but the audience should meet them for the first time face to face with your hero.