F2 to H1_pls help!!

[susu]

hi all!

I would like to know about F2 to H1 status change. Can a F2 start working once H1 is approved, before getting his H1 get stamped?

My friend told me that some times u have to get visa stamped from home country or others to get new I-94 and to start working....
and some times u can start working without any further stamping...
What is required will be written in the approval form..

we are confused..

Pls help us....

Thanks all in advance...

sus..