Saaney,

First thing to clear is EB2 v.s H1B, completely two different things. H1B is an employer based petition to hire qualified prospective candidate for the position and the whole application process is different, starting from LCA (Labor Certification Approval) to filing application on April 1st. H1B is entirely lottery based, and you get to know about the lottery approval on Sept, if you are lucky to win this lottery. (Certain quotas (caps) are assigned for Bachelor Degree and Masters degree, check online for caps.)

EB2 or EB3 is another petition for green card process. It starts with PWD (Prevailing wage determination) and follows labor filing, 140, AP,485 and takes much much longer time for decision.
So, bottom line is your PWD from EB2/EB3 cannot be portable to file for H1B, you have to file LCA seperately before H1B.
If you are planning to file H1B on this April, act now, ask your employer to file LCA and you will still be able to file H1B on April 1st, if you start working on the documentation.
If you need to know more, send PM to me.
Good Luck.