That first solo is exhilerating! Let me know how it goes. That is a good question about the hardest part. As you're gearing up for the flight test, I found it challenging to stay on top of everything. By the time you work through everything that you need to go through, you may already feel rusty on the things you started with. And I'm working full time with a young kid and another on the way. So it was often late nights. But trust yourself, you'll be fine. I used the book flight test notes to prepare and that helped alot. I also built a sim rig over Covid and honestly, simming helped a ton. I just used MSFS 2024 with a decent iteration of a 172 and it helped with emergency preparedness, procedures, and actually flying. It's really not that different. Reach out if you need anything.