I started one day before you, and candled last night. What can I say ... I was bored! My husband was at the Alabama/Florida game, and my two boys were at Gramma's house for the night. I'm not used to being all alone, and that was the most daring thing I could think to try at my age.
Anyway, I did a Google search for "candling chicken egg day 3" and found a TON of great photos, so I felt like I knew what I was looking for: the "spidery veins" with a little black dot in the middle. And, lo and behold, I saw them in all three eggs! It gave me some confidence that I'm doing something right! It also gave me someone to talk to while all my guys were gone. I said, "Hi, eggs! It's your new mom!" I'm not sure if it's like babies where they tell you to talk and play music and read, but what the heck, right??!
All the information I read said that you can candle every day if you want to: you can keep them out of the incubator for a half-hour if you wanted, but on the downside it appears that the longer they are out (up to a half-hour), you run the risk of it taking longer for them to hatch. I don't want that!
Now that I've seen that there's definitely something in there, I'm going to try to wait until day ten. But I guess I'm just trying to say that if you want to candle, just do it. Just don't drop the egg!
Keep us posted, and good luck!