You can leave the employer at any time really, after you get your green card. A reasonable period of employment after getting the employment-based green card is about 90 days. So you can leave and do not need to return if you do not wish. It will not have any negative consequences. Please let me know if you have any additional questions or how I can be of further assistance to you in this matter.
Answered on Jun 21st, 2012 at 7:26 PM