1. Two weeks ahead: Four hours of Bible Study / exegesis.BigThink
2. A few days before: Moving from 'what does the text say' to 'what does it mean to me' (life related)
3. The Day before: Six hours editting it down.
4. On the day: Four x1 hour preaching it.
Never yet had to preach a sermon four times in one day, though our church is going back to back services in the autumn so twice is going to become more common. I'm definitely a get ahead kind of person - the four hours at least two weeks ahead is a great idea.
Step 2 seems the really hard step - turning an outline of the passage into an applied sermon, Keller excels at this. And then editting is definitely time consuming but pays great dividends for making the word stick.
Can't help but think it's all too easy to go from Step 1 to Step 4 without doing 2 or 3 at all.
So far Step 4 has only ever been preach it once, though we're going back-to-back services in September so here comes preaching twice...