L1B Travel while H1B Petition in Progress

[subhanat]

Hi

I am on L2 Visa and applying H1B (with COS) for the year 2008. I have to go to India on Sep 08 and plan to come back on Sep 08 itself. If my H1B Petition gets approved, can I start working for my new employer from Oct 1st with the approved H1B?

Please let me know

Thanks