one day

(literally) plan your day during the morning, plan your year during New Year's / early planning is the key to success

(rare) the first day of the month

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

A solar year, the time it takes the Earth to complete one revolution of the Sun (between 365.24 and 365.26 days depending on the point of reference)

(a duration of) one year / an unspecified year in the past

one, 1 / the first in order, foremost / the beginning / the best / a kind of; one of something / (card games) an ace / unity / the bottom string of a shamisen or other Japanese musical instrument

(idiomatic) to make plans

each person

the first day of the month (solar or lunar calendar)