I don't like #1 because you will, from what you've stated, be presenting documentation establishing that you are ineligible to return to work for your former employer. Your new employer's appointment letter isn't going to cut it. Also, I assume that your petition did not include a request for consular processing and, if not, you should not leave the U.S. while the change of employer petition remains pending.

I don't like #2 for the reason that you cannot document that you remain employed by Company A, and if you show that you're authorized to work for Company B starting on December 1 they may well respond, "You can enter up to ten days in advance of your start date. Come back then."