be on the cusp of something[singular] to be at the time when a situation or state is going to change 处于某事即将发生变化的时刻 The country was on the cusp of economic expansion. 该国正处于经济扩张的当口。
be on the cusp of something• With plans to add another 100 staff by April, it is on the cusp of breaking into the big league.• They will be on the cusp of puberty.
→ be on the cusp of something at cusp(1)