Does H1-B Cos stands valid if L1-B cancellation is done on/after Sep,20th?

Hi Saurabh,

I am working in Company A on L1-B visa and I have my H1-B CoS approved with Company-B starting Oct ,1,2013.

  1. If I resign Company A on Sep,20 and they immediately file my L1-B Cancellation will I get 10 day grace period to start on H1-B on Oct1,2013?

2.How long does it take to process L1-B cancellation?

Thanks in advance for your time.