Oliver Sutton

Then is a word to be taken seriously, but when?

Then usually works as a working-class version of subsequently, or the more up-market trope of at that time, but such word play introduces the potential for querulousness as in "at what time?" The reader expects the writer to keep abreast of the time sequence in a story, even mess with it because most readers don't expect things to observe strict chronology in narratives because things as such don't observe strict chronology in reality. At the very least, most of us are in the past two or three times an hour, remembering or trying to remember things we needed to have done, and are looking into the future an equal number of times in anticipation of some event, whether it is a survival-oriented anticipation such as when is lunch, or some kind of sensual gratification as in a view of a pleasing sight or smell or experience.

When you think about it, then is on a level with all of a sudden or its second cousin, suddenly, or its relative from the country, at that moment.

Things happen, right? Things happen because your characters cause them to happen by things they've said, done, not said or not done. You didn't remember my birthday? You didn't remember our anniversary. You didn't remember that I'm allergic to____. Things happen because people do things to your characters or try to do things to your characters. Things happen because you have hit some resistance and need to introduce some new element into the story. While it is true that such an invention could easily be a just at that moment moment or even a just then then, you don't have to prepare the reader for it because the reader is there for the just at that moment moment or the then then. In the real world, it would have to be the just-at-that-moment moment, which is a pain in the ass to punctuate, all the more reason for not using it.

You have given this all some measure of thought. Fair is, after all, fair. Just as it is all right to occasionally split an infinitive (providing you do it smoothly, which means using an adverb), there are times when then is appropriate, particularly when someone one of your characters has a romantic interest in asks the leading question, Then what? At that point, the smart thing would be to end a chapter or a scene because you'd have pretty well established the probability of the reader staying with you to the next scene or chapter.

Of course, then you'll have to deliver. Something will have to happen. So why not let it?