I don't think it would work als a name, kid would be bullied. (what do they call you at night, or what day are you?
Monday, tuesday....)
Maybe as a nickname for
Dale,
Dayton or something similar.
Ranking the names:
Fay, cute name for a girl
May, cute name for a girl
Kay, love this for a boy.
Ray, like this as diminutive for
RaymondJay, nickname for
Jason or
James or other J. name
Tay, not sure, kinda like it, maybe as a nickname.
Bay, don't like it
Day, maybe as a nickname
Gay, I don't think a kid would be happy these days with this name, but I like the (original) meaning.