This allows the peep time to orient itself inside the egg before pipping. This will help bring the humidity up to help the peeps hatch. I know it will kill you not to open the incubator 1000 times when it's this close to hatch time, but it's not good for the peeps. If you haven't bought an incubator yet, invest the extra couple bucks in the picture window model. Good thermometers can be found at a few places.
Camera stores carry reliable thermometers.
The best investment you will ever make in your hobby is a good, accurate thermometer for incubation. When picking out a thermometer from a batch of them, you should look at them all to see if they are reading exactly the same temperature. If not, save your money, or make sure they can be calibrated. The Rhode Island Red is the most successful dual-purpose bird of all and remains an excellent farm chicken. They are very good layers of brown eggs and are known for their hardiness and ability to produce eggs even in marginal conditions.