I am brand new to hatching eggs.
I candled on day 7, sure I was going to see chickie growth. What I saw was a blob in each and couldn't see any veins. I was dissappointed and figured none were fertile. Since my banty cochins were hatching them, I decided to let them have them for a few more days and I would check again just to be sure.
At day 14 the dark mass had grown, the air sac larger and more distinct and all signs pointed to little chickies growing.
I am so glad I didn't go with my first impression and toss the eggs...glad I waited and checked at day 14!!!