Thank 863211. One more question.

Really appreciate your answer. I see what the risk is for working for new employer before Oct. 1 now. Exactly I have to stop work for old employer by Jun 30. I will get the 3 mouths cap until Oct. 1.
My question is it is possible to let my old employer do not cancel my old H1B until Oct. 1; or my old employer has to report it to USCIS immediately after Jun 30. My new employer has good relationship with the old one. Do you have any suggestion for my situation? Thanks a lot.