Ask YC: Rejected and planning for next round.

4. Get a better idea

-- or --

4. If you believe in your idea, forget the demo and build the software!

It might be better just to plan your product and business and begin executing right away. If the stars line up and you can apply to YC next time, go for it. But I wouldn't go planning my business around YC's schedule. Seems to me like that's backwards. YC should be an enhancer of your business opportunities, not a driver.

I'd just go ahead, move to SV and build your product.