What should I expect from AIT using the AC2RC option reclassing to 31B?

SPC Harveston Piggee, expect to get up early in the morning and do PT, and then learning after chow. As for drill weekends talk to the members of your unit, because each unit has its own quirks. Stay flexible and enjoy life.

Do you know what Reserve unit you will be going to? That will determine what type of training you will do during a battle assembly (drill). There are combat support, guard, law and order, and various other types of Reserve MP units.
AIT will give you a broad understanding of all five of the major functions of a MP: Police Intelligence Operations, Internment/Resettlement, Law and Order, Area Security, and Maneuver and Mobility Support. Once you arrive at your unit, you should receive training as to what your specific unit does. Yes, some months may be administrative and full of classes. But, keep in mind that, as a reservist, your unit is required to complete month required tasks that other components have a whole month to complete.

Here is some good information. It will give you a good idea of what to expect during your reclass:
http://www.wood.army.mil/usamps/Training/BMPC31B.html

Send 1SG Healy a message if anyone can answerer your questions, He is the man.

Battle Training Assemblies (drills), are basically (and for the most part) 30 days of AC wrapped into 2-3 days of a given weekend. Your AIT can vary on how prior service (relcass status) are treated/considered. you could either be placed in the same barracks or different ones. You could be under the same restrictive standards as the IET's or given a little bit more free reign. All depends on the school house.