I am on currently working on H1 for Company A and I am planning to move fulltime to Company B which is very big company and my join date is 2/20. Company B attorney sent the h1 to USCIS couple of days back and got the receipt number in the email. My question is if I tell Company A and they revoke my H1 immediately(they can since employment is at-will), will it effect my transfer with Company B or will I be out of status as my joining date with Company B is 2/20 . I need to give notice to Company A immediately and I want to know when is safe time to tell this ?