one day

to start a journey; to embark on a trip; to set forth; to hit the trail

(rare) the first day of the month

being from a certain place / coming out

resolve, decide, come down (on a course of action)

personal determination, resolution

one day, 24 hours / the daytime, the period from dawn until dusk / (figuratively) a short period of time / one day, someday, an unspecified day / the first day of the month

all of a sudden, all at once

sudden

suddenly