Maybe listening would be a better word than waiting....the book is always in my mind: characters are chattering away, the plot gets livelier or tighter, a new scene comes.... sometimes I'm just mulling something over, or trying to figure something out.
I usually wake up with ideas--I scribble them down while I'm having breakfast. Then I might go for a walk, ride my bike, or just putter around the house -- I really don't know WHAT I do in the morning and I think I waste a lot of time. But maybe it's not wasted. Who knows. At some point, though, I sit down at my computer and get to work. The actual work part is where things happen, but nothing good gets written unless I put the quiet time in first.
Once I'm actually working, I don't usually waste a lot of time (unless it's a distracted day and I DO have those: I think someone described them here a few months ago). At this point, I'm no longer waiting. By the time I sit down at my desk, I know what I want to say and the time at the computer is for saying it. Often -- usually, even -- while I'm working more details -- or better ways of doing things -- pop into my mind, and that is a rush.
But for this to happen, I need some kind of routine and stability -- money worries and big decisions are particularly deadly. I think one reason it's sometimes so hard for me to get started on a book is that once I am IN this routine, leaving it is quite disruptive. I don't want to see friends. I don't want to go anywhere. Sometimes I don't even want to wash my hair or get dressed! And this is of course an isolated way to live-- and I think pretty common for artist of all kinds: maybe not. But it is a dilemna for some of us: how do you balance things?