How far out from my school date to reclassify does my unit have to send me back from deployment? Am I able to PCS before I reclass?

All MOS retraining is TDY enroute. If you have dependents you’ll be authorized to choose to return to clear after training, it’s still TDY enroute even if you return to clear. If you don’t have dependents you will clear prior to reporting to AIT. You will need to do your levy packet, get your physical orders, and get a manual DD1610 approved with your Line of Accounting approved from your Division prior to reporting.

I was deployed when I got selected for OCS. I found the appropriate reg and learned that I had to be back stateside no less than 90 days prior to my report date. I let my chain of command know (showed them the reg) and I was allowed to go home early with "Torch party" so that I would have enough time to clear and PCS to Fort Benning (yeah, I don't know why I was PCSed, as I had been branched Engineer by DA, but I was. Heck my PCS orders had my rank as 2LT, which the ACT system still lists me as)

Since you have a school date you can apply for 160th already and get your follow on assignment narrowed down to 3 locations.