There is a product called Marking Magic that is great for a dark color like this when using a stencil. It is found only at quilt shops and is in an aerosol can. You lay your stencil down on the fabric and spray the white chalk on to the stencil. It is some what adhesive and does not wipe off during the quilting process like regular chalk does. To remove it when you are done quilting, you simply mist with water. It is used by many hand quilters because it does not come off until you are ready to take it off.
Mindy