You may switch employers at any time. If you wish to maintain, H-1B status, your new employer will need to file appropriate transfer. Otherwise, you will need to wait until your EAD arrives before you can work. If you choose to work with your valid EAD, you will be out of H-1B as if the day your employment ceases. You are nonetheless authorized to stay in the country because of the pending Form I-485. You can read more about adjustment of status at http://myattorneyusa.com/adjustment-of-immigration-status.
Answered on Jul 26th, 2016 at 2:58 PM