This is just my experience. Every workplace is a bit different, but I think my answers will be generally applicable.
- Are people going to be annoyed at me if I fidget, move around, and pace a lot? Yes
- Are people going to be like, constantly looking at my screen? Am I going to feel judged the whole time Yes
- I have the classic ADHD "do double the work in half the time, do nothing the other half". Am I going to be judged on my work output, or how busy I make myself look?
Busy work is going to be the most important aspect of your time. Looking busy without being busy is an important art - If I have downtime, would it be acceptable to read a book or something?
No - If I have a chat with my coworker sitting next to me, is the whole office going to hear it? Am I going to be interrupting and bothering everyone? Everyone will hear and short conversations are often considered fine
- Did you disclose ADHD to your boss? Did you get any accommodations for it? Not ADHD but anxiety and depression. They don't really care. Make sure you do the paperwork for FMLA to cover your ass if behaviors become disruptive in your environment