YOu need to talk to your HR - This is very very important! If yoru priority date is not currect yet, you cannot file EAD. You must continue to extend your H-1B status (which can be extended for 3 years after your I-140 approved) until you can file your I-485 (green card). Only at that time you can file EAD with I-485 then you can stop H-1B extension. But usually we alwasy suggest to keep your H status till you get your green card. The reason behind is in case your green card has problems you have your H status back up - you may have time to find other solutions.