An ACD means an Adjournment in Contemplation of Dismissal and means your case is put over or postponed for six months or a year, after which it is administratively dismissed as long as you don't get re-arrested in the meantime. You can at least try to get an ACD first on your own and if they give it to you without a lawyer, then you're home free. If not, you should ask for a lawyer to be assigned to you first and then you can hire one if needed later.
If this is Brooklyn, when you show up in court they will ask you to hand in your DAT paper. At some point a Legal Aid lawyer will call your name out and bring you into the hallway to speak to you and ultimately represent you. Obtaining an ACD is entirely probable and hopefully you can get it without any conditions but there is a chance the DA might ask that in exchange you attend a program called STOPLIFT or do a day of community service. You certainly would need a lawyer but I wouldn’t worry about hiring one just yet, Legal Aid will probably be able to take care of it for you.