minibarn

When preparing a the layers of a quilt for quilting do you square up the backing and batting? I know that they need to be a few inches larger, my question is more do you actually cut them to that size. For example I just prepared a quilt that is 48" square, however my backing and batting are several inches larger and I did not make sure they were square, just larger. Is it better to make sure they are square and cut those pieces to 50" inches, or does it make any difference how much bigger as long as they are bigger? And is it critical that they be square. I plan to machine quilt this myself if that makes any difference to replies on the subject.

I hope my question makes sense.

Thanks,
Jenna