4 stepper.  I move my right foot slightly ahead of the ball.  I sort of slide it past the left foot and as it passes I start the ball either forward or down (depending on what speed I'm trying for - when I'm trying to amp it up I start with the ball pretty much fully extended before I move my feet).
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"I do desire that we may be better strangers."  Willie the Shake, As You Like it(III,ii)

Five stepper here.  I start the ball with my second step.  I think part of the reason you might be seeing guys starting the ball later, is to create more leverage at the line by having "late" timing, thus creating more revs.  The problem I see with this is that it can cause you to "yank" the ball down to the release, as opposed to just letting it fall naturally.  If you can "wait" for the ball and not yank on it, you're okay being late.  I've tried being late, but am much more comfortable having the ball in time with my feet.

It's all about the bowler and what they feel suits them best, it's all about consistency and no one is better than the other.  I've seen power players with four steps (Robert Smith I think) and strokers with six steps.  Textbooks will tell you to drop the ball into your backswing as soon as you start the first step of your four step approach, but a Textbook is just that, a two dimesional object in a 3 dimensional world, 4 if you count time.  Not that it is of any significance buy I happen to be the texbook example.
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Don't trust the moustache

4 stepper. ball moves out with first step n comes down once my first step is done, while the 2nd step is coming..
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PeRfEct GaMe!!!

"No one is perfect.."
Scores don't mean anything...