OPT - H1B - change of Employer

[febsenthu]

Dear Attorneys / Immigration Experts -

I am currently on OPT STEM extension which expires on Jan-2014. I am currently working with employer A this year Apr-2013 employer going to file my H1 under Premium processing.

I am actively looking for fulltime Job.

Assuming If I get my H1 petition approved on this Apr-2013 Since its under PP. (I knew RFE but lets Not consider tht)

And Assuming if H1B Quota for both Masters and Regular got over in Apr or May -2013.

If I get Full time between May - Sep -13, Let me know can I join as OPT in that company and Transfer my H1B petition.

Please shed some light on this