1) Yes. There is no grace period after denial. There is no way that you can guarantee approval. So you would have to leave immediately. If you want to come back, you can have a new company or the old one file a new H-1B for you where you would process outside of the U.S. Sorry, it is the risk that you take.

2) You would have to do the transfer to Company C before a final denial of Company B. So it may be possible that if you appeal the denial of Company B's petition, it would not be a final denial and you may be able to transfer from Company B to C because technically you would not be out of status.

3) No time. There is no more grace period like there used to be.

Please let me know if you have any additional questions. I would be happy to answer them for you without additional charge, if not, please do not forget to click ACCEPT. I am not paid a salary. Clicking accept is the only way that I can get paid for helping you. When you click accept, you are not charged again and we can continue to communicate without additional charge if you have a few follow-up questions. If there is a delay in getting back to you it is either because I am answering other questions or I had to log off, but I will be back with you as soon as possible. If you would like to request me in the future, just put my name on the subject line. Positive feedback for my service to you (not the state of the law as it is) is always appreciated as well as any bonus if you think I deserve it. Thank you.

I believe that this would be possible and unfortunately, I cannot tell you how long you would have, but probably much more that a few months. However, you could not stop working for Company B and then look for a job and then file with Company C. It would have to be just like if you were going from Company A to Company B. There cannot be a gap in your employment. You must maintain that employment to maintain your status. Please let me know if you have any additional questions and please do not forget to click accept. Thank you.