Mrs. Owl laid her first egg sometime between 11:15 and 11:40am on March 22nd. She didn't really incubate it much, and spent time standing over it. Eastern Screech Owls generally start incubation with the second egg, which should be laid around the 24th.
Another interesting puzzle we have is that Acrobat Ants seem to have showed up, and are crawling over the egg. We have had Acrobat Ant infestations before, but never so early in the season. Usually we notice them near the end of nesting. And we have never seen them on the egg. While Acrobats don't bite, they can compete with the owls for stored food. So we'll have to keep an eye on this situation to determine whether there is anything we ought to do. So far, it hasn't seemed to bother Mrs. Owl in her dealings with the egg.