I'm a first time DM (3.5e), and, being a passionate writer, I decided to create the entire campaign and campaign setting myself. It's been good fun, and I have about 12 pages of (elaborated upon) ideas for it. However, I'm starting to worry that I'm becoming too specific. My original plan was to get several dozen pages of ideas for my campaign setting (easy enough), then compile it into a formal "specification" that would basically establish the whole state of the world. (Originally I had planned to write it out normally, but I've been thinking now that I'm gonna use Obsidian Portal or something like that. Not too important.) Following this idea, I set some backstory for the world politics in general, and for the powerful nation that'll be the setting for most of the campaign. I decided it was a good time to draw a map of the continent, so I did. I ended up with about eight countries, including the main one. Within the main country, I drew in fifty districts. Then I look at it again.
At that point I realized that I would have to go through and name fifty districts.
Now, it's not impossible. But I've never done this before, and it doesn't seem necessary. I know that the PCs will need to know the names of three districts within an hour of play, and that's it. The others could come later. Do I need to worry about them now?
This is a bit more general, as well. What level of specificity should I write it at this point, when I haven't even had a game with my players yet? As a first-time DM, I really can't foresee what I'll need. Any suggestions?