You can file EAD application

together with your I485, if you are able to hand in your I485, no problem, you will get an EAD. But once you use your EAD, your H4 status will be invalid. But 485 pending status is enough for you to stay and do anything you want in the States, that's called AOS (adjustment of status). If your spouse's I140 is approved already, it is relatively safe for you to use your EAD. Otherwise, keep your H4 valid as long as you can.