What is 13F AIT like for a prior service Air Force E-5? What should I expect as a 13F NCO?

Are you sure you don't have to go to Basic? 13F is an OSUT meaning the Basic and AIT are all together. Usually AF prior service have to go to Army basic, in fact usually everyone except Army and Marines who recently separated have to go through Basic. Even Army who have been out a few years.
I'd hate for you to show up expecting to be an AIT insert and find out that you'll be spending a few extra months at Sill

It is a steep learning curve getting to a unit as a E-5 fox, as you’ll more often than not be thrown into an FO slot or a Team Chief slot if Manning is down. Get real comfortable with map reading and basic call for fire , then everything else will come. Don’t be afraid to ask fellow NCO’s on help with any kind of fire support planning and Skill level 2&3 tasks . You never stop learning in this MOS . Go to JFO as soon as possible , that’ll be some good experience to have as a FO/FSNCO. Good luck brother .

SSgt Austin Beams Below is one post about 13F AIT. You can search on 13F AIT to review the other posts.

https://www.rallypoint.com/answers/do-you-have-any-suggestions-for-things-to-study-or-know-before-going-to-13f-ait

AIT will teach you the bare minimum of what a private is expected to know if I’m being honest. It’s an extremely competitive MOS among NCOs so you will have to be proactive. Best advice I can give reclasses is find a peer E5 or even a high speed specialist who has had FO time (they likely have schools that all E5s are expected to have such as JFO) and pick their brain. Be humble and take the time to learn. Being an E5 you will be an FO or you will be stuck in the FSE if you fail to impress early. Best of luck DM me if you want any specifics.

As others have said steep learning curve. I was an FO with a JFO cert when I was in. You will only be taught basic calls for fire in ait. You can look in the old 6-30 for an idea of the other fire missions that you won’t cover. Additionally we work hand in hand with rotary wing so you should also get to know controlling methods and the CFF for them as well. You will be expected as a E-5 to know registration missions, coordinated illumination, destruction, sweep and zone, and quick smoke missions. Wouldn’t hurt to also learn the marking mission for close air support as well. What I was taught as an e-1 was to buy a flight book and write down all the calls for fire. That way when you need it you just flip to the page you need and fill out the template. Best of luck!

UPDATE: I didn’t have to go to BCT, I went to reception to get all the basic admin and medical stuff done and then I was sent straight to AIT.

I just reclassed to a 13f last year
1) the school for you will pretty much be like a normal day in the military. Show up for PT, then after your released show up to the school house at 0900. You will be treated differently than the IET soldiers, as you have experience, but will be held to a higher standard as well. There is a whole lot more to learn than what they teach, and you will have a lot less time to learn it once you get to your unit since you are already an nco
2) I reclassed with a guy who transferred from the airforce. He was a fire fighter and had to go through BCT, but he said he was treated way different than the privates. He said he had his own privacy, kept his phone, and didn’t have to do all the stupid basic training BS, just PT and and the classes and range stuff, but experiences vary on that based off of you even have to go and where they would send you