As far as I know, H1 gets effective from October (in your case October 2013 if accepted??). If you leave US before it's effective, you cannot enter US in H1 visa 10 days before the effective date (Oct 1st) even if it has been approved. You need to enter in OPT (extended?) or some other status.

I have a related question. I heard there's an application you can fill to expedite your H1 stamping in Nepal. Does anyone know anything about it? I need to know because I think 10 days won't be enough to get everything done.

Thanks in advance.