L1B to H1B COS, RFE and COS effective date

[maxkei]

I am currently in US on L1B. My I94 will expire on Sep 2016. I applied for H1B COS and got through the lottery,
and have responded to a subsequent RFE request. My question is, will L1B to H1B change of status happen immediately
on the day of the approval of the case, or is there a grace period for cases approved after October 1st due to RFE.