I try to add a label to every quilt that I give as a gift. The one's I keep I'm not so good at adding a label.;
I add mine after the quilt is quilted. I usually use an extra block or some extra scraps from the front of the quilt, use my embroidery machine to "write" the label. I then sew it right sides together with a lightweight fusible interfacing, turn right sides out and Iron the label on the quilt. I then go back and stitch the label on the quilt. The interfacing helps to give me a turned edge and keeps the label in position to sew it on.
On the label I say who the quilt is for and why, ie: birth, wedding, comfort, dates of event if birth or wedding and my name and date quilt was finished