How to Porting EB3 to EB2 ?Is it possible to use before Priority dates

[AnushaNari]

Hi i am new to this forum

I havefew questions.Write now my GC is processing

My priority date on EB3---july 2010

I140 is filled on EB3 categoty

similarly EB2 labor is filled---may2011

1.Can we port EB3 to EB2 ?is it possible to porting

in which stage it is used? how to port? ca u expl!!!