The useful starting point
An article published today may describe a release or experiment from months earlier. A later update can also change the article without changing the date of the underlying event. Treating the publication timestamp as the event date can distort a technology timeline.
A small step to try
Keep separate fields for publication, update and event dates when they matter. Check whether an article explains what changed in an update. Avoid turning an old demonstration into a newly established capability. A small dated note helps readers understand when the evidence was produced and whether your summary refers to the original report or a later correction.