I've heard of them candles every day 1-18 and left after lockdown... But the more you candle the greater risk of dropping one, possibly on others, tranfering germs and accidental flipping of egg to small side up. Be careful. Always handle eggs with CLEAN, DRY hands and never if your tired.
if in doubt... LEAVE IT ALONE. I am candling every 3-4 days until lockdown because my humidity gauge is wrong and I'm also making a video diary with my 8yr old daughter for her class. Rule of thumb is days 7,10,18... More or less as you feel. Good luck with your babies.

