How can someone currently at OSUT, under an active duty contract, transfer to NG or Reserves in order to go to school in the Fall 2018?

Sounds like he is contracted active duty and I really don't see him convincing his commander to grant a transfer to the reserves (via a form DD-368?), especially when he is a brand new private. It's kind of bad planning to apply for college and enlist active at the same time, unfortunately a contract is a contract. If the school has a online program then it might be salvageable. Also if he did manage to transfer, he would probably have to sign a new contract that would cancel the old contract out. Meaning any bonuses he received may have to be paid back. It's really a question for his unit, some S1 people on rally might you give you more information but they cannot predict what decision his unit will make. Plus his MOS makes a huge difference, Reserves are usually more support MOS and NG are more combat. For instance if he was 11B then he would have to go NG.

Personally, I would convince him to stay on point and finish his 3 years. He'll be 21 (?) when he gets out and have a much better sense of himself and what he wants to do with his life. The Army is not just about serving time, it's also about developing yourself, maybe not like a dream school way but it does teach you some hard lessons that are just as valuable.

Good Luck.

So basically he's wanting to renegotiate his contract, immediately after signing it? Good luck with that. I'm not aware of any process to shift to the Reserves or NG immediately after going onto AD.

He made a commitment to the Army for 3 years, it's up to him to use those three years to learn and develop himself. 3 years isn't that long of a time considering most of the first is his time as a private is basic, and AIT. then most of his last year is separation and out processing.

I'm assuming your SO is probably in his late teens early twenties. Encourage him to use his time in the Army to his advantage, take online classes, use his TA, get leadership experience. Who knows he may come to find out that he is more interested and enjoys his time in the Army.

He can always go NG Reserves when his contract is up.

Honestly you should let him be an adult and make up his own mind on what to do, if he is old enough to Enlist he's old enough to make his own choices in life.... cut the umbilical.