mox

Mox is an indeclinable adverb with two settings. Looking forward from now it is "soon, shortly, in a little while". Inside a narrative it is a plain sequencer, "next, then", and the historians use it that way constantly: primo ... deinde ... mox strings events together without promising that any of them happened quickly. Translating every mox in Tacitus as "soon" will make his campaigns read faster than he meant them to.

It needs no preposition and no case after it, and it can sit directly in front of a prepositional phrase: mox post bellum is good Latin for "soon after the war".

Unlike most of the high-frequency Latin adverbs it barely survives into the Romance languages, which built their words for "soon" out of other material. If you know Spanish or French, this is one you have to learn cold rather than recognise.