Beginning, Middle, End -- 初，中，底

Chinese uses the words beginning, middle, and end after month and year to specify which part of the month or year:

月初 -- beginning of the month
月中 -- middle of the month
月底 -- end of the month

年初 -- beginning of the year
年中 -- middle of the year
年底 -- end of the year


Other vocabulary:

初中 -- middle school
初期 -- in the beginning, early period

初中年中就結束了。
[Middle school ends mid-year].

文化大革命初期，人民都贊成政府的政策。
[At the start of the Cultural Revolution, everyone supported the government's policies].