Belinda~~~ Also, I have learned, that not all eggs will show veins as early as the third or forth day...even though it's from the same clutch, or shipped order. I usually see veins on the third or fourth day, but have had to wait to see anything for 6 days being the earliest on others. Yep, best to wait it out..you will know for sure when they come along..and if you see a spot..that's a very good sign!
Also, the yolk usually stays around the middle once the egg gets going..I have had them float to the top, the once it started, stayed around the middle. So, you never know..6 or 7 days will tell the story. It's just the waiting..even after all the eggs I have hatched, it's the waiting that is so hard when you want to know if an egg is good or not.
Of course, if you see anything that looks wet, or a yellow sticky color on the outside of the egg, then get it out of that bator! I have had this happen as soon as the very next day after putting them in. This is my first year of having that happen. Had heard of weeping eggs, but now know what it looks like.
Good luck, sounds like you have some fertile eggs in there.