If you haven't got the egg in an incubator, you need to give it back to her. It won't develop unless it's kept at the proper temperature. So you won't see any veining until it's been set for a few days, either in an incubator at around 100 degrees, or under the hen.
I've read that most people candle around 7 or 8 days, and veining is usually visible by then. I think I've read that veining is visible in a white egg around 5 days.