The problem isn’t a 3.8. It’s getting B grades- and one in hum, one in stem. (I.e., not just a hum hiccup for a stem kid.) And OP rightly recognizes this happened in soph and jr years.
If anyone can fly without the 4th year of foreign lang- or with B grades in that- it’s kids taking college post calc courses. There often isn’t room in the hs schedule.
What AP did he get the 4 score in?
This is up in the air. A little more complicated than just looking at the 3.8. With only the info we have here, I’d say, apply to the college he most wants. Early doesn’t add points, they still focus on the kids they want most, who best meet their full expectations, send a bang-up app and any supps. Those kids benefit from an early decision. It doesn’t makeup for some other issue(s.)