In general, you WANT the stitch holes to be as tight as possible while still stitchable ( is that a word)? Make sure the chisels are going all the way through, so that the back-side is up onto the tines - past the point so that it's fully open. As mentioned by @chuck123wapati, you can wiggle the needle a bit to stretch the hole some, as it will have shrunk back some after it was punched. When you thread the needle, double or even triple pierce the thread to help keep the "knot" an inch or so behind they eye of the needle. If the knot creeps up to the eye, it'll be far more difficult to pull through.
Hope that helps!
- Bill
