Just let them pip on their own, thats your best bet. I cut on day 55 and incubate at 89 degrees and mine usually dont come out for 4-6 days after that. If you cut on day 53 and they arent ready yet they could potentially be sitting in their eggs for a week or so afterwards; if you are not there to clean them out and keep an eye on them for that long bacteria will start growing in the open eggs and you will have issues.