I wish I could just speed up this process, or avoid it altogether, but oh well. I wrote about 3,000 words today - or rewrote at least. I always seem to need two versions of the first 100 or so pages, one that's terrible that just kind of helps me get my bearings, and then one that actually will serve as the rough draft. Today I got to the end of my rewrite of those first 100 pages, which means I push on tomorrow.
The novel is now about a third of the way done, and the second act can be hairy too. I do a lot of tinkering with the first as I write the second, because I find that the only way to keep the story rolling through the second act is to make sure every plot thread has a good foundation in the first act. The middle of the book is no time to introduce brand new conflicts.
By far the easiest part, for me, is the third act. When I've done it right, all of that naturally follows from what I've set up before. I wish I could just fast forward there, but the only way out of this process is through.