I like to use a halogen light to candle, the first day after incubating you really should not be candling I suggest wait to day 4/5 for beginners, plus if you have a light colored egg shell you can see in the egg better. More experienced hatchers may look in an egg and know what is going on sooner. this is after day 1 see the red dot? This pic is why people wait until day 5 to candle day 3 is faint looks like a peace sign if you look hard. this is later on day 3 same egg. day 4 the egg below is day 4-5 near the top you see the spider web day 6 you would see an eye.... after day 8 or so it starts to get too dark to see in egg. but then you can still watch the air cell grow as you candle. this doesn't photo well day 8 but it was swimming back and forth sometimes you could see the eye. day 9 I like to mark in pencil where the air cells are on days 7, 14, 18 on day 18 the air cell should dip down slanted like on the above egg- if it is not a large air cell or slanted, it isn't ready for lock down. When you candle on day 18 the pointed tip should be dark. If it is clear then the egg has too much fluid that needs to dry and on that egg, I would wait until it is dark before starting lock down.