Different PERM and JOB location

[vijay14]

I am working for a company that has offices throughout US and I am based in location  A and my team is in location B. My priority date is Jan 2011 (from previous employer) and now my current employer is starting my GC process and I got to know that for PERM there is a shared recruitment position in Location B which suits my profile and they can file my PERM right away and eliminate prevailing wage , ads etc. My manager is willing to relocate me to location B and am also ready to move once my GC gets approved. I was assuming that GC is for future employment and I can work in location A till I get my GC and then move to location B. But my attorney is saying that I will have to move to location B and start working in location B even before I get my GC.

Can someone please let me know if we have to be specifically be working in that location at the time of filing or can we move after GC is approved? How do I convince my attorney to that?