How does Chen "work"?
You're not meant to go late with Chen. If you're picking Chen you want early ganks (preferably kills) and then transition into pushes. Your 3 main ganking creeps are the Centaur with the stun, Troll with the snare, and Hellbear with the slow. If you cant gank then farming is fine, but with a hero like Chen you really want ganks to be effective. Eventually you'll start pushing towers. For that purpose, the Wildwing and big crit wolf are both great. Wildwing gives armor to all your allies, and the big crit wolf gives 30% dmg to all allies.