See how to calculate dates to set eggs for hatching. Baby chicks born under a waxing moon are said to be stronger, healthier, and mature faster. 

HOW TO CALCULATE DATES TO SET EGGS
Baby chicks take 21 days to hatch. Chicks born during certain times of the year are said to be healthier and mature faster than chicks born during other times of the year.​ Chicks born under the waxing moon generally during the signs of Cancer, Scorpio, and Pisces are best.

• To ensure that chicks are born during these times, determine the best days to “set eggs” (to place eggs in an incubator or under a hen.)
• To calculate the best days to set eggs, find the three fruitful birth signs. Find in your Almanac or purchase your own Moon’s Sign Calendar.
• Using only the fruitful dates between the new and full Moons, count back 21 days to find the best days to set eggs. .

​Example: If the new Moon is on June 12 and full on June 26. Between these dates, on June 13 and 14, the Moon is in the sign of Cancer. To have chicks born on June 13, count back 21 days; set eggs on May 23.

Reference: ​http://www.almanac.com/content/setting-chicken-eggs-moons-sign