Once you file 485, you can file EAD (I765 any time) after 485. Give yourself at least 3.5 months, since there is a rule: if you filed your EAD and 90 days passed and you still haven't received your EAD, you can go to the local INS office to get an interim EAD on the spot. The interim EAD is as good as a real EAD, will be valid for 8 months. Then when the real one comes, it will be effective after that 8 months. Good luck.