Timepoint vs. time point

When speaking of a point in time, what would be the proper usage:

"Timepoint" vs. "Time point"?

This funny confusion comes from my life as a programmer: While one of our style checkers enforces "timepoint" instead of "time point", another style checker contradicts that and prefers "time point" over "timepoint"...

Very nice! Methinks you have unearthed a compound word in the making.

I did a narrowly-focused (1995-2005) Google lit search for both time point and timepoint, and learned both terms seem to be found most often in technical writing − often describing scientific, statistically-driven experiments.

The two-word time point is running far ahead of the one-word timepoint (by a ratio of about 10-to-1, at this point in time, at least). However, who am I to argue with the likes of Campbell and Heyer, genome researchers who wrote:

Three microarray hybridizations were carried out for each timepoint.

I don't know anything about microarray hybridizations; I'm not going to intervene as their grammar police.

The main problem with your style checkers is not that they disagree; rather, they should allow both as admissable forms.

It is customary to say, simply, "point in time" — as both "timepoint" and "time point," while understandable, are not used much.

If you're talking about programming exclusively, then the question is probably too narrowly scoped for this SE site. Whatever your company uses is what you should use. Note that style checkers probably looked up "timepoint" and didn't find it, but the two-word confection of "time point" renders two very basic words that check out just fine.

Although the Google NGram viewer has its flaws, in this case you may notice that "timepoint" and "time point" gained what currency they have as computers came into wide usage. One may infer from this that the technical aspect is the reason, which supports the contention that you should use whatever your audience is most comfortable with. Since "point in time" still leads by a comfortable margin, it is the term you should favor for non-technical uses.

Disclaimer: There is a usage of "time point" in music, referring to the start of a tone in a tone row. This usage, coined by Milton Babbitt in 1962, probably adds something extra to the "time point" curve.

in context, to the best of my knowledge 'timepoint' is not part of universally accepted terminology, therefore using it does not offer any benefits over 'time point'. Personally, I would use

time-point

and would prefer 'time point' over 'timepoint', although I don't think I can provide any arguments that could convince your style checkers:).