Can anyone describe 17C AIT?

I'm about a month ahead of you, schedule wise, so I can give you insight up until then. I haven't gone into BCT or AIT yet, but I have done a lot of research.

I remember the ASVAB requirements for the army 17C were about 110- you should be into that with a 91 percentile, so all you have to do is confirm your ASVAB at MEPs by answering the same questions the same way you did (except it's a shorter test, unless it decides to make you retake it). After that there's a computer/cyber specific ASVAB addon section to take, which you will need to score I believe a 60 on. I didn't know what to expect, but passed because of my strong background.
I can tell you to expect A+, Network+, and Security+ subjects to be brushed over in the test. Once you pass that, it's just a matter of getting through MEPs.

Basic research says there's 25 weeks of training in Florida, and then another 20 in Georgia, for a total of about 45 weeks. After that you can supposedly collect special pay in addition to basic pay. It's essentially a paid education, so I have no complaints, personally. I know it's what I want to do, and getting paid to confirm and develop my knowledge is acceptable.

When preparing for BCT: Pushups, Situps, and Running are key for the APFT. An advantage in those will be helpful. I'd advise doing exercises for "Hip Flexors" as much as possible, because a lot of people will find those muscles exhausted, and it will lower their scores.

In my case, but it may not be all cases, my contract is a bit over six years. It said five all the way before then, but it changed to six. It may have been a mistake, it may not. I calculated it to be five years + training time, so I went with it. You could probably get them to double check, change it down to five since that was the original number, or might not run into the issue at all.

In terms of my research:
I know you spend a lot of time in a SCIF in AIT. You spend 9-10 hours a day on the training, and have a two hour "study hall" at the end. Job wise, I'd say this is probably something you either can or can't do. To me, everything makes sense. Supposedly it makes no sense to some people. You'll know what you can do. If you like this field, I've decided it's worth getting into.
Salary is comparable to private sector in the entry stages, and you have pretty nice benefits. Great training opportunities as well, especially if you want further college education through the GI bill.
Supposedly there's low retention in 17C, because everyone has decided they can make a lot more money in the private sector when they get out. There's a research paper a company did on it, actually. Meaning you'll likely be considered a "talent" that is sought after.

In terms of general promotions, you can look up the promotion requirements for each rank (they may not be entirely accurate), and you can get a decent understanding of what goes into E5 and beyond promotions. Everything up to E4 is practically guaranteed.

Good luck!

As stated previously, you will be spending time at Corry Station in Pensacola, FL for about 6 months and Ft Gordon for another 6. They are phase I and phase II respectively for 17C AIT. For JCAC (at Corry Station), Joint Cyber Analysis Course, they will teach you from the ground up for everything that they want you to know. The course is designed for people with no computer knowledge. However, it will help you if you are strong in logic, math, and programming. If you want to prepare for it, you can look up on YouTube for JCAC prep.

Not an exact answer to your question, but relevant nonetheless. I'm a 25B AIT student at Ft. Gordon, and I actually lived in the same barracks as the 25C for about 5 weeks while my company was waiting to move into our new barracks. So I might be able to provide a bit of insight into the second half of your AIT training, weeks 26 - the end. The 17Cs I knew were all pretty laid back people. By the time they got here they were disciplined and it seemed like a lot (not all) of the bad eggs that can get a platoon messed up had already been weeded out. Everyone there seemed to know that they wanted to be there and needed to work to get what they wanted. Their sergeants were pretty laid-back in general, and the barracks were pretty nice. 2-3 to a room, private bathroom, public dayroom and computer labs on every floor, and a laundry room every couple of doors. They seemed to have WAY less formations than we did, but that might have just been me not seeing the whole picture.

Overall, my experience with the 17Cs who make it past Florida and come to Ft. Gordon is extremely positive. I think that if you sign for that MOS you can expect to be working with a group of motivated professionals. The few I knew earned my respect in the short time I knew them. Best of luck to you, and feel free to message me if you have any questions about BCT or the AIT lifestyle!