Gearhead wrote
(sorry Aja) it would be smart to actually loosen the strings by tuning them down, tighten the rod and then tune back to pitch to check. It is not very hard as long as you don't overdo things...
Sorry, I should have clarified! I meant while you wait for it to settle overnight it might be better to keep the strings in tune. I friend of mine once adjusted the truss rod but forgot to check the tuning. Turns out the strings were tuned up a full tone and as soon as he tuned it properly the neck changed position again, requiring readjustment and leaving it overnight again to settle.
But I did not think about loosening the strings during the actual adjustment, good tip! ?