Finch Not Sitting on Eggs All of the Time?

I have a female and male zebra finch. They mate all the time and this past Monday (5 days ago) she laid her first egg. Then two days later another (Wednesday); now nothing else. They sit, off and on, on their two eggs, but not consistently. I am wondering if more eggs will be laid because I generally hear of females laying eggs every day not every other day like mine? Also should I candle them to see if they're good since its been 3-5 days (since she laid them)? What should I do? How long should I wait to remove them if they don't sit on them consistently?

By Joey