It takes about 3 months once you filed your I-485/I-756. You should keep your H1B status as long as you can.
This answer is of a general nature and should not be relied upon as final, nor is it intended as legal advice. Consult with a qualified attorney before making any legal decisions. Gen Kimura, (832) 247-6932.
It takes a few months to get the EAD, when you have it you can work for anyone, however, if your adjustment application is denied for any reason it will be revoked and if you have already left your employer you may have issues with your H1B. Because marriage applications are complicated you should file with an attorney, my firm handles such cases.
Law Offices of Nicklaus Misiti
212 537 4407
Legal disclaimer: The statement above is general in nature, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship.
I agree with my colleague.
This information is intended as general information only. This communication does not establish an attorney-client relationship between me and the asker.
It takes about 90 days from the filing of your I-485 and I-765 to receive a work permit. You must wait until you received your employment authorization card before you can start working independtly from your current H-1B status.