I am looking for a single word meant to represent the evening, much like "tomorrow", "today", [missing word], and "tonight". I do realise that "tomorrow" doesn't actually mean "this morning", but the word I'm looking for is a sort-of replacement for "tomorrow" for a fictional world where mornings and days are a thing of the past and it is engulfed in eternal nights.
There already exists a question which asks for an antonym to the phrase "on the morrow", which I link here: Antonym/Opposite of "on the morrow", and the word "eve" came up, which would look utterly horrendous as "toeve" for my purposes.
Is there an existing word in the English language that could substitute "morrow" of "tomorrow" to be related to evening time?
Sample sentence: What I couldn't finish tonight, I will not finish [word] either.