ASK PG/HN: Question on advantages of applying early

Hi From the description on applying at "http://news.ycombinator.com/apply", I quote

"Early submissions have a significant advantage because we have more time to look at them and engage with the founders.

Could you please elaborate on how you engage with the founders who have submitted an idea but plan to refine the application (perhaps significantly) before Oct 19 deadline? I am working on an idea, have reserved domains but I do not have any web site running yet. I would probably have that happen very close to the deadline. If I submit an application right now, how would yc engage with me? Does this involve some kind of feedback on the idea/application itself?

Thank you!