Non-immigrant workers in the United States are unable to start working until they have an Employment Authorization Document (EAD). This document can be obtained immediately after your visa is approved. With your EAD, you can work in any U.S. company legally for as long as your visa is valid. Spouses are also eligible to receive an EAD if they qualify.
You need to renew your EAD every time you renew or extend your visa.