We have a pair of Budgies that are very well bonded. The male is constantly trying to feed the female. She is coming in and out of the nest box a lot, flying back and forth, chewing everything is sight, and eating a lot more then normal. The cock is bobbing his head a lot and tapping his beak on the perch. We have not witnessed them mating but I would be surprised if they hadn't. She has also been digging around a lot in the nest box. Do you think she is going to lay eggs soon?

sounds like the start of nesting - i would think in about a week you could see eggs.

How long have they been in the cage together?

 

They definitely sound bonded. Are they in full breeding condition? The female's cere (fleshy part above her beak) should be a even light tan colour and the males should be a even vibrant blue (no light blue parts)

 

If all of these are a yes, then you should expect eggs within 10 - 14 days after pairing them up