It might seem early but I had a hen on a nest opening morning she skirted off I looked around and seen about 9 eggs I left the area undisturbed I'd say she came right back
A UT graduate research student did a study in Southern Mid TN a few years back, earliest nest incubation they found was April 8 with April 27 being the median. Thats incubation, not initiation (which averages April 9-22 for the SE).