Request for change in first name on 18th Nov 13 in approved petition (time)

I recieved my approved H1 petition on 26th July 2013. Prior to my stamping on 14th November 2013, Our team realized there is a minor spelling mistake in my first name. As per process we raised a service request for name correction at California Service Center and my employer recived a request id for the same on 18th November 2013. How much time does it take for such a change request ?