"Hilja" is not a rare, poetic word in Estonian, and it does not mean quiet. It is a form of the adjective "hiline", which means late. For example, a mother might tell her child "Ära tule koju liiga hilja" - don't come home too late. When something happens hilja õhtul, it happens late in the evening.
- https://en.m.wiktionary.org/wiki/Hilja -