I personally just let them hatch on their own. The reason why yours are just now pipping instead of around day 56 is because you are incubating at a lower temperature (85 degrees vs 89/90 degrees). If one has already pipped, the rest should soon follow. If you do decide to cut, candle the eggs ahead of time so you can hopefully avoid any veins. Make a small slit so that air doesn't dry out the egg and bacteria doesn't get into the opening.