I have done it most of these ways. I have attached before quilting, after quilting with label or pigma pens.
I also write my name in pigma pen somewhere under the binding wrap.
I would hate for a quilt to be taken (not that mine are prize worthy) and try to make something permanant.
I have also seen on this site somewhere I think that someone signs the quilt with a pigma pen and also attaches a label over that.
Kyia