I personally leave them be as long as the pip has broken the membrane so that they are getting air. Most of mine that pip on the wrong end, end up hatching just fine. I see most of the issues when people step in too early out of panic. It can take up to 24 hours after pip to hatch. As long as they have air from their pip I wait 24 hours before stepping in. They need that time to finish absorbing the yolk and all of that work from hatching is what strengthens their body.