If I am making a quilt for a particular person and know that while I am making it, I put a piece of white fabric on a piece of freezer paper, print whatever I want on the label on the white fabric.
Before I quilt the quilt, I sew it onto the backing, usually lower right corner, about 8 inches above the bottom of the quilt and about 8 inches in from the left side of the quilt. Then I quilt the quilt.
The 8 " up and 8" away from the lower right corner was arrived at after I used this method and wound up trimming half the label off the quilt. Sometimes I don't measure so well...