H1B COS New I94 Effective from Oct 1st

Hi ,


My wife was on F1 status and she got the H1B approval in June with a COS which will be effective from Oct1st. Due to unexpected reasons, my wife went to India and she is coming back to US on H4 visa on Sep12. Does she need to do a change of status in order for her to start working from Oct1st or can she start her work from Oct1st as her new I94 will be effective from Oct1st. One of the attorney said, she can start working from Oct1st. Can you please comment on the same. Lot of my questions got resolved through this forum. Thanks for the great work you have been doing.