The simmering stage, that's what I call this.
It's once you've gotten past that first bit that you've imagined the novel started with. The opening scene introducing your characters has been written. You've gotten past that first painful bit where you doubt you ever had an idea that could sustain a novel.
Suddenly as you're writing a drop of new knowledge is dispensed. His sister's an alcoholic? Really, I didn't know that but it sure makes sense with the stuff I want to write later. He's suffering from depression? Wow, that's great because I couldn't figure out to take them to those darker places. This is the stuff novels are made of. Happy coincidences. They happen in life and they happen in books too.
I'm a bit behind on my word count. Only *cough* ten thousand words or so *cough*. I've got time to catch up though and suddenly, with a few 'happy coincidences, things look much more possible then they did yesterday. I have some facts to play with now and I'm sure they were just the tip of the iceberg.