the shrinkage has more to do with the batting and the density of quilting than it does with the actual fabrics- the way to avoid that problem with table clothes/toppers is to skip the batting- or use a layer of muslin or pre-washed flannel for batting.
if you want to pre-wash a pre-cut i would use a net bag- and do it on gentle- figure on sitting for awhile ironing- each and every one will be a crumpled little mess- you will have to smooth and press...i never pre-wash pre-cuts- i only use them for projects that i'm not worried about shrinkage- or bleeding color.
i do pre-wash most yardage.
but it is the batting that causes most shrinkage surprises in finished quilted projects. :thumbup: