Moving to location where PERM was filed after GC Approval?

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My GC recently got approved for a location A for my current employer as my perm was filed for location A. 
I am currently working in location B for the same employer in the same role in which my GC is approved. 
I did not file AC21 as I was not eligible to file it.

1. Do I have to move back to location A?
2. Do I need to move back to location A in a certain time period after GC approval?
3. What if my employer wants me to continue working in location B?
4. Can not working in location A have any consequences at the time of citizenship application?