What’s the process of being released from the NG onto active duty? How will 19D AIT/OSUT be, since i’m prior service?

So let me tell you my experience when I transferred from the NG to active. I was a tank turret mechanic (45N) to infantry (11B). OSUT
I showed up to BCT at week 3 and did the rest of BCT and AIT. Along the way I was an outcast because I didn’t go through the first two weeks with the unit- so there were some fights. That’s ok cause I got in a bunch of fights when I went to BCT the first time. Then the DS accused me of being CID. The first week I got three counseling statements in one day. I couldn’t do anything right. So they claimed. It was hell. On graduation day the DS looked at my uniform and said- oh you were prior service? Why didn’t you say anything. Yea right- so just be ready to get treated like crap and work your butt off. Graduation will be that much more special. Good luck!

You may be made the "Platoon Guide" even if they do not, make sure that you don't mind helping the younger trainees. You will be a leader in that group, because you have finished an AIT, you have been in a unit and you have some leadership experience.
Being a mentor, sometimes, just happens.

First off, why would you want to be a 19D? Half the guys in my troop are scouts cause they were forced reclas. It's usually the other way around; 19D reclasses to 25 series or something that pertains to the outside civilian world. If you want to go indef as a 19D or go in to law enforcement later, then that's a little more understandable.
OSUT, though, you have a slim chance of having to redo the entire OSUT (Red all the way to Black phase), depends when you get there. But you should be able to go straight to black phase (the AIT portion), just note black phase isn't entirely like the AIT you went through.
Message me directly if you want more details.