change job after 485 approved

Hi, All:

My I485 was approved recently. I have been with the current firm (they sponsored me the green card, EB2 regular) for almost 4 years. My question is that if i need to work for the employer for at least another six months before i can change jobs.

I really appreciate any help.

Also, want to say good luck to everybody who is still waitting for their approval.