I just read somewhere not to candle between 11 & 14 days so not to interrupt the embryo which is moving at the length axis of the egg during these days. So much to remember!!!!
Don't bother remembering that one... Candling an egg does no harm at any stage as long as you use clean hands, handle the egg gently and don't let it cool down for too long (anything under 30 minutes should be perfectly fine)... You can candle day 1 through day 21+, multiple times a day if you really desire, no harm or foul... Broody hens turn the eggs all day and night from day one until they hatch, and they are not always that gentle about it, they move the eggs generally 50+ times a day, and they get off the eggs regularly every day to eat and drink... Nature doesn't follow a set of incubation rules, and incubators are tame compared to what a broody bird does to the eggs
