Lawyers advice is to wait until April and if they still have not called for an interview, go to court to force Immigration to issue the green card. I know one person who did that and it took 3 years so I am hoping thats not the case here. Usually they waive the interview if they thought the marriage is real. He has prior marriages and his current wife's income is low so it likely got flagged for an interview. He already has work permit and advanced parole so in a good working marriage, he could wait for years. Unfortunately if they flag you for an interview and they never call you you can stay in limbo forever. Marriage issue is due to wife having mental issues and not taking medication on time. It seems like he is running out of patience.
I am US born citizen happily married with 3 kids. I looked into sponsoring him for my business and his personality is a good fit unfortunately he would not meet US immigration employment guidelines for sponsorship. I advised him few years ago to go to Canada and try his luck there, he decided to get married and have a real relationship. I respect his decision. May be I should advise him to talk to another attorney.