Don't go to your interview without having consulted an attorney who obtains a copy of your disposition. That question is very difficult to answer. The problem occurs when you apply for naturalization. If you obtained your green card on the basis of employment and you did not stay with that employer long enough INS might think you have committed fraud. The law does not specify a time.
Most attorneys recommend six months to one year.
I recommend a year. The real question is whether you and the employer intended your employment to be permanent. I am contemplating to get married with a person from my country overseas. You would need to file for her at your consulate in your home country. I think the form would be an OF-156.