I know it happens differently for different people. Some people feel like that from the first chapter, the start of a new adventure in writing. Others it takes longer before it fully clicks, burning through many pages before finally "getting it." I know for me books have taken varying amounts of time before I love them (Death's Aria was quick, Paradise Seekers was instantaneous, Effulgent Corruption took nearly a whole Part, if not more). All the way up to it feels like you are treading water, just sort of writing but not getting anything out of it. Like you've been setting stuff up but you aren't sold on it yet.
Then it sells you, and you can finish the book.
It took A Straight Cut 30,000 words for me. I'm not saying anything before that was bad, I'm saying it didn't draw me in. Usually the whole "magic moment" happens when I discovery write a really good scene. When I know everything that's going to happen its hard for me to be excited. When characters surprise me or dialogue ends up being better or witter than expected, I get sucked in. And then I know the book is possible.
If I don't hit this point quick enough (or the early parts are super-sludgy), than the book can get dropped. Like what happened to Ringforger and what I'm worried has happened to Naught But Glass.
But yeah, that moment. It's great. I'm pumped to write now.
It's also countered by the inevitable "30,000 - 50,000 word 'I HATE MY BOOK' moment," which I swear every manuscript has once it hits that point (this isn't just me; I have proof in the form of other authors [published ones, even] confirming my theory :P), but we'll save that for when I hit it in A Straight Cut. Considering it took 30k for me to get to the "yay I love this book" moment, I'll give it around 75-90k for when I start hating its guts.
So that's it. I'm sorry I've been abandoning this blog, but my video game blog is thriving! That's been both good and bad; I started it as just a fun writing exercise, and now it's getting some insane amount of hits every day and it's only been a few months. I wrote 100 reviews for it already, though, so that's pretty good.
See you in the slump! :P