Where does “однажды” come from?

однажды (Russian) comes from Russian -жды, from Old Church Slavonic -жды, from Old Church Slavonic шьды, from Proto-Slavic jьti, from Proto-Balto-Slavic eitei, from Proto-Indo-European h₁éyti, from Proto-Indo-European h₁ey- — to go.

однажды (Russian): once, one day, once upon a time; once