Hi Diana. It could be that she is only going to have 2 eggs this nesting. If it is warm enough she may not need to be on the nest much. If you see her coming and going she has not abandon it. One suggestion, don't do nest checks near dark, you don't want to scare her off the nest in the dark!
There is a great website all about Blue Birds and how to help them. www.sialis.org good luck!

Diana,
First,you should only be checking the box in the afternoon,The morning is when the egg laying takes place,you don't want to flush her from the nest justs before dark either,It may be difficult for her to fine the box in the dark which is really not good.Now about the 2 eggs,She only lays 1 egg per day until her cluch is layed,she will not start incubation until all the eggs are layed.If you check the box tomorrow afternoon you should have 3 eggs.when she is done laying (maybe a few more days)she will begin incubation.At that time I would limit your monitoring unless you suspect a problem.If you know when she lays her last egg you can caculate the hatch day,12-14 days later,give or take a few days.It is best to write down these important dates,for your reference.Please visit the link below for lots of info.Keep us posted

Matt

Here is a link that might be useful: Bluebird link

Matt, Diana wrote "She only laid 2 eggs though--and its been around 1 week.". I have the same situation http://nature.gardenweb.com/forums/load/bluebird/msg0520452422139.html

I worried about this, too, as it seemed to me that she wasn't on the nest enough. She must have known what she was doing though, because she successfully raised 5 little ones!

I did't know about not checking the box at dusk, and once when it was about time for the eggs to hatch, I wanted to check on them. Thinking that she wasn't in it after gently tapping on the box, I opened it and nearly scared her to death. (nearly scared me to death, too!) She was hunkered down on that nest of eggs, wings spread and covering the whole thing, with determination to protect her little ones. I guess I'm lucky that she didn't fly out in my face! But I certainly learned my lesson.