H1b , OPT extension

[karnam.mahesh]

Hi,

My employer has filed my H1b this year(2016), which has not been approved yet.
I applied for OPT extension and it got approved.

What happens to my OPT extension if the h1b gets approved?
Can I use up my OPT before going on H1b? If Yes, how do I do it?

Thanks in advance,
Mahesh