H1 B Petition Transfer before stampping


I want to transfer my H1 B Petition from company A to B before the stamping (current petition status is Case was received).

  1. How to processed on this from company A, i need any approval or Documents from Company A?.

  2. What conformation i need from company B in this case?.

  3. Is there any chance that company A can cancel the H1 petition? ( i have a bond on this and i am ready to pay the amount).

  4. Can i start this Transfer process before leaving the Company A ? ( i will join Company B for sure).