What tips or advice do you have for someone reclassifying and preparing for 17E AIT?

SGT (Join to see), congratulations! I recall your previous post a few months ago about dropping the packet. You already have the primary tip I'd offer -- show up with the right attitude. The 17E course has exponentially changed from 2021 to 2022 (first formal 17E AIT training at the CY School FGGA) and 2023 (modernized EMS curriculum and training to deliver effects supporting large-scale combat ops and multi-domain ops). It's important that you get "tips" from current practitioners or someone familiar with the training at the Army's Cyber School.
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Secondary tips (you can dabble in these topics ahead of time ... but please don't over-dabble):
1. If you are not up to speed on the Army's concepts for large-scale combat ops (LSCO) and multi-domain ops (MDO), read up on these concepts. Army and Joint pubs are good starts (FM 3-0, JP 3-12 are good).
2. You will be educated on the EMS (electromagnetic spectrum). You can do basic research ahead to familiarize yourself with theory and perhaps some of the technical aspects.
3. Do some basic reading about "software-defined radios". Just knowing what these are would be a help. But, you will have plenty of lab time learning this topic.
4. You will also have labs that teach/instruct on basic electronics. Key word is 'basic'. This is IET/AIT after all. You'll rapidly progress as your 17E journey unfolds in the operating force and during your PME training over your career.
5. You can't really prep for this one but you'll learn/train on EWPMT (Electronic Warfare Planning and Management Tool). Controlling/managing EW assets ISO offensive and defensive electronic attack, targeting, and Spectrum Mgnt Ops.
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Hope this helps.

Lateral moving to another MOS is a great opportunity but as a Sgt you will have some struggles. You are moving into an MOS where you are expected to be a leader and majority of your peers have spent their whole career in the field you just entered into. Be humble and be ready to learn. I lat moved from Infantry to Communications as a Sgt and the best thing you can do is leave the machismo and ego at the door. You are still a Sgt and a leader but you are also a new guy and student. You have to walk the narrow line of being that solid leader but also humble beginner in a new trade. It's ok to learn and admit what you don't know but you don't have the buffer of being a new PFC who can keep tripping on your feet and be allowed to learn from constant foul ups. If you screw up it will land directly in your lap publicly so start out taking baby steps. Don't rush things. Slow is smooth, Smooth is fast. Proficiency will come over time.

SGT (Join to see) Here is a previous post that should provide information.

https://www.rallypoint.com/answers/how-can-i-best-prepare-for-the-17e-course