Cut a strip of paper the same width (or less) than the width of your square punch.
Draw a line along the length of the strip in the middle, then mark equal distances.. this determines the width of your chevrons... I used the marks on the craft mat as a guide. Do this on the wrong side.
Put the strip in the punch diagonally, lining up the centre horizontal line with the corner and the vertical lines with the sides.. punch..discard the punched piece..
Line up the lines on the strip as before and punch...flick the pointed ends of the paper out of the way of the punch or you will cut off the points..... there's your first chevron!
This will work with any size of square punch and any width of paper ( as long as it's not wider than your punch)