Don't remove the papers 'til you are ready to applique. I starch my fabric and lightly press, haven't had any problems with the outside losing shape (but do pin and tack...a lot). I know some very old quilts have been put together with the papers in, but I don't think I would risk it. When washed the paper could get pretty revolting and maybe clump or somehow spoil the design or compromise the fabric. This is how I was taught, so this is how I have continued, would be interesting to see if others do it differently.