予 (Kanji for beforehand)

Onyomi

I put a nail in YO mama beforehand, so she wouldn't struggle too much.

予定(よてい)

an informal plan ★★★★★
予 (beforehand) + 定 (plan) = 予定 (an informal plan)

an informal plan (like to meet your friends for a movie)

予約(よやく)

reservation ★★★★☆
予 (beforehand) + 約 (promise/ roughly speaking) = 予約 (reservation)

reservation, appointment

予報(よほう)

forecast, prediction ★★★☆☆
予 (beforehand) + 報 (data) = 予報 (forecast, prediction)

A child is ONE year old.

The complete kanji is complete even WITHOUT the 'one' radical.

MAMA was around before baby.