One bit of advice I would give is don't over do the candling, some people just can't resist and are in there daily, I don't like to bother the eggs that much, in fact I only ever have brown or green eggs anyways so I cannot see anything in the early stages like you have here so I skip all candling until day 10, by then you can easily see the embryo and it swimming about in the egg. The only reason I would candle earlier than day 10 is if I was concerned my air cells weren't developing properly