Company C's H1B petition transfer to company B without working for company C?

[nikhilnash]

I am currently working on OPT with employer A who is filing for my H1B (no premium). I have a job offer from employer B and C. Employer C is filing my H1B(in premium category). Employer B could not file for me as their internal deadlines were gone. My question are:

1) If I join employer B on opt, and if my H1B is approved for company C, can I transfer that H1B to company B without even working for company C? 

2) If yes, can this be done before 1st October or it has to be done after that?

Even though company A is also filing for my H1B, there is a good chance that I will not get the approval notice before the joining date of company B. Also since I will mostly quit company A before the result of their petition, they will revoke my case.

3) Assuming the visa has to be transfered only after Oct 1st: Now I will be working for company B on OPT, but since my H1b is now aproved for company C, my OPT will be cancelled on 1st Oct. In this case, do I need to quit company B and then join again after the H1B has been transferred?

4) What is the best possible steps to take in the case which i mentioned. I ultimately want to join company B as that is what I want to do.

Also, I am applying for OPT extension which will be valid till December 2016. I know I can just skip all this and join B on OPT and file next year. But with so many applications coming in, I don't want to loose out on this filing.


Please advice. Thank you!