Actually, you should get a copy of your file, and meet with a lawyer now. Rather than wait to see if an NTA arrives, you could be prepared. Have you been on probation? When does your probation end? It is not uncommon for an immigration hold at the final probation meeting. Was this a felony or misdemeanor? Were you advised of the consequences of a conviction as an LPR? This are all questions that could have a bearing on the outcome. Good luck.