If I want to reclassify to 17C, is 25N a good foundation? How can I best prepare for it and how long would it take to get a school date?

I've been thinking about it and I want to do it just had a few questions. Is 25N a good background/foundational MOS? How can I prepare better for 17C? About how long would it be to get a school date? I would greatly welcome and appreciate any and all help. Thank you!