It's usually on before Chinese New Year, Lantern Festival and other festivals
Usage of on:
1、Date:
on 12th September(9月12日)
2、Weekend:
on Thursday(Thursday)
on Monday morning（星期一上午）
3、周末（仅限美式英語）：
on the weekend
on weekends
扩展资料表示时间时介词in和at的使用规则
in：
1、 A certain time of day :
in the morning (morning)
in the afternoon (afternoon)
in the evening (evening)
2. month:
in October (October)
③3. year:
in 2013（2013）
4、 Century：
in the 21st century（21st century）
5、 Season：
in spring（春天）
in summer（夏季）
at：
1、 What time is it:
at one o'clock (1 o'clock)
at 6:30 (6:30 p.m.
2. point in time:
at midnight (12 midnight)
at?dawn (dawn)
at?sunset (dusk)
3. holidays:
at Christmas (Christmas)
in summer
At Christmas:
At Christmas:
At Christmas (Christmas)
At Christmas:
At Christmas (Christmas)
at Christmas (圣诞节)
④4、Weekends (British English only):
at the weekend
at weekends