Debatable. Why? I'll explain:
Now here are the good reasons: farming artifacts right now, at AR 40 will make your team stronger (making it so when you start hardcore farming at AR 45, it'll be easier). The artifacts you get, while they won't be the best ones, will still give you a good damage boost.
But it also isn't using resin to the maximum efficieny. If you care about efficiency, I personally wouldn't go for farming artifacts until AR 45 (when you're guarenteed a 5* artifact per run).
Now, if you have extra resin, I would build a second team (for Spiral Abyss), and if you still have quite a good chunk of extra resin and nothing to spend it on, might as well go for farming artifacts ig