For what it's worth, let me tell you my story... Back in 2002, I adjusted my status using consular processing. I was employed as a management consultant and had worked there for a total of about 5 years. In mid 2003, during the depths of a recession, business was not that good for my employer and there were simply too many of us at the "Manager" level. In order to prune the ranks, they were very tough on us during mid-year 2003reviews and I received a poor review, despite always having received good reviews previously. This was their way of signalling to me that it was time to go. (The unwritten rule in the Mgt Consulting industry is "up or out", and since the former path was blocked I opted for the latter). I ended up leaving my employer 10 months after I received my GC, and there were certainly no hard feelings - they released me from reimbusring them the cost of the GC and in many ways I was doing them a favor by self-selecting out.
Before I left, I came on this board to ask advice of other members. Many of the responses that I received quoted me the "6 month rule", the general length of time beyond which it was generally deemed safe to switch employers. However, members did caution that each case is different and that it depends on one's individul circumstances for leaving. In my case, even JoeF, a former member of this board and a veritable encyclopedia of US immigration law, seemed to think that 10 months with the sponsoring employer was good enough. Not being satisfied even with that, I contacted a good immigration attorney at a firm that had helped my wife and I previously. Without really explaining the entire situation to him, I just indicated that I wanted to switch employers after 10 months. His response was, "you're fine". I took him at face value and resigned the next day.
Back at that time, the "6 month rule" was often quoted in these forums - that was the general rule of thumb for leaving one's employer following receipt of a GC. I subsequently came to learn about the 30-60-90 day rule which deals with what your "intent" was at the time you got your GC. If I understand this precedent correctly, most job changes following 90 days of employment with the sponsoring employer are deemed acceptable (i.e. no intent to defraud the government) by the USCIS, meaning that they would not come after you for changing jobs in that period. I realize that AC21 may have subsequently changed the rules a little bit for everyone but if you want to take a conservative approach, then consider waiting 3-6 months before changing employers. While this may cause you some hardship now, it may save you some hardship / stress later on.
I am about to file my N-400 in just a few weeks, so I have no idea how all this will ultimately play out with the USCIS. All I can offer is what opinions I received at the time I received them. If this becomes an issue for me, I plan to explain the reason for the job switch, show them the performance review and remind them of the economic climate at the time.
Whatever choice you make, do your best to gather as much documentation as you can to support any statements or claims you may wish to make in the future. Best of luck to you in whatever you decide.
