Being prepared

I've put down Course Corrections until I finish Ping's story (needs a name) and/or hear back from Viable Paradise (some combination thereof). Edits trickled off on March ninth or tenth. Started Ping on the fifteenth. About 2600 words in three nights. First scene is a problem: character wakes up. ARGH. Keep going anyway. Fix later.

One question that I've seen asked in writerly circles is: How do you know when to start? Not where to start the story, but when do you know enough to actually start writing. Some people like to go seat-of-their-pants and just dive in with inspiration to go on. You can always fix it in revision, after all.

Personally, I want to go in prepared. I started this story with three outlines -- the events, the emotional arc, and the two combined -- two half-met main characters (Ping and Jeri), a handful of supporting cast, and a couple hundred words of various details (trajectories, speeds, notes on cancer, back story).

Here's where I cheated: already partly knew Ping and Jeri (as I've mentioned) and the supporting cast is also recycled from supporting cast in Hacker's Reboot -- Lissy, maybe Seamus will be there too. My only genuinely new characters are Ping's grandmother, Popo, and the source of the problem, Blu. Popo's mostly a plot function hashed up with bits of my own grandmother. Blu is also largely built from necessities and planned personality points... we'll see how it gels.

Here's where I didn't cheat: the central question of the story, which I will try not to answer too clearly in the actual telling. I need to know the truth, though. The five or six days I spent planning this involved a lot of option-weighing. I settled on what the truth is, worked out how it will present itself, made some guesses about what the characters will think when they meet it, and that's enough to start. For me.

Can always fix it in revisions.

How do you know when to start writing?