On day 18 of the chicken egg incubation period, the eggs should be close to hatching. The chicks inside the eggs will have fully developed and will be using their beaks to break through the shell. This process is called pipping, and it can take several hours to a day for the chick to fully emerge from the egg. The chick will then rest inside the egg for a few hours to allow its wings and body to dry before attempting to stand up and move around.