ticketed for drug/narcotics consumption

My 21 year old son was at a house party that was raided by the police. There was prostitution happening and illegal drugs/weapons were found. The owner of the house and several others were arrested. My son was not arrested, but he was ticketed for a drugs/narcotics violation. I believe it was for consumption. This is my son's first offense. He is a college student and is not a resident of MI. My question is, should I hire an attorney now, or should I wait for his arraingment? If I hire an attorney now, is there a chance he/she could get the charges dropped? If not dropped, is there any way to have them eventually removed from my son's record? He is studying to be a teacher and will not be employable if this stays on his record. I am doing this long-distance as well, so any suggestions on finding a reputable attorney in MI would be greatly appreciated. Grrrr what a mess!