How to align the crosswise edges of a fabric?

I have to sew seven large tablecloths of a teflon coated cotton fabric. Measuring and cutting them all would be a lot of hard work so I tried using the crosswise grain to cut it, but when I tried to fold it, it wouldn't align properly with the selvage. So I remembered this technique my sewing teacher used, she would stretch the fabric along the bias before laying out the pattern. So my question is, does this stretching align the crosswise grain? would it if I got someone to help me be able to straighten out these tablecloths, or do I have to do the measuring? - the cut I've made follows the crosswise grain exactly - I have the selvage on both sides of the fabric