Seems kind of late in the season. If they haven't even finished the nest yet it would be hard to say when the eggs get laid. If it's the barn swallow, I found this information
Nesting Facts

Clutch Size
3-7 eggs
Number of Broods
1-2 broods
Egg Length
0.6-0.8 in
1.6-2.1 cm
Egg Width
0.5-0.6 in
1.2-1.5 cm
Incubation Period
12-17 days
Nestling Period
15-27 days
Egg Description
Creamy or pinkish white, spotted with brown, lavender, and gray.
Condition at Hatching
Eyes closed, naked except for sparse tufts of pale gray down.

Thank you tmc2009,
I still don't know what's really going on,...I could be seeing activity, flying in and out 2 or 3 times within about a 15 min. period, then nothing for an hour or more. I don't want to go in now, ...I'll know when feeding is on with high activity, it's still a possibility.

Here the male..

This has been a very strange nesting year. Normally, we have both bluebirds and tree swallows occupying a single house most of the season. This year, they have come and gone and have been replaced w/other tenants. If they are like my tree swallows, they are not bothered at all by human activity. I even inspect their nests occasionally, and it doesn't seem to bother them. In fact, owners of martin houses are encouraged to frequently inspect the hatchlings for mites and other issues. Additionally, I've have many encounters w/barn swallows while fishing under bridges. They could care less about my presence. Right now, I've got a Carolina wren who took over my bat house. The bat house blew down in a storm, breaking off part of the top. I put it on its side on a table next to a big woodpile to fix, but that wren decided to nest in it before I could get the roof back on. He also is not too concerned w/my proximity. I'll wait until its done, I guess.

Regardless of the strange year, I must say it has been a very successful nesting year, judging by all the juveniles. I don't ever recall seeing so many.

Great to hear for a good year!
Looks like it will turn out alright, regular in and out feeding traffic now!
And my first Purple Martin pair raised a family,... after two years trying, just fledged!

Congrats on getting martins. I've tried for the last 4 years now and can't get them to stay--even tho' I work to keep the sparrows out. They visit and inspect frequently but don't occupy. There are so many trees where I'm at. I'm considering moving the site to the pond dam where it's a little more open.

Yes, that might work, keep on trying, make sure to put the house up high. All have fledged here, one's in a while the family, [both] returning and checking things out, perhaps for memorizing next year's visit. I'm thrilled for 2 new species this year, making it 3 total with the tree swallows. When the tree swallows have fledged, they're gone for good, a little disappointing,..but, they're early in spring!

Towards evening today a couple went into the root cellar again,
not sure what this means, I'm new to this species,.. any idea?
I'm pretty sure nesting is over this late in the season,..do they roost?