My lawyer told me to stick with a current employer for at least 180 days

there is NO recommended period. once you are a permanent resident your are free to take up any job.

V C, I read something that if you leave earlier you may have some problems later. What if the employer reports you that he offered you a job through GC and then you left ...

180 days my lawyer told me because later one you will have issue becoming a us citizen… it will make you look as untrustworthy… you use someone for your benefit

Can leave job if you can prove it's for your betterment. Like doing business or similar job with better pay, better company, etc. All they want to know quitting was reasonable as no one can legally stop you to leave job for growth. Hope this helps.

I wonder if after 180 days can I leave my job and become a contractor, or I need to stay employed?

there is no 180days thumb rule. it's lawyer's suggestion. IO can question about anytime during your GC period if they find to be suspicious. I would spend some dollars with good attorney before making a switch. Lawyers will suggest based on your case history and compelling reasons to leave your current job by law. Decision would be yours..

thanks guy, I guess the problem changes completely if I am dismissed by the employer right?