Yup, agree with all the above. Give it time. Starting school is exhausting. It took 5 weeks for DD when she started going full days to adjust. We moved bedtime forward each week until tantrums stopped. We could finally move it back to a more reasonable time after about 6 months (we had been picking her up, feeding her dinner, and putting her bed for the night).
DS starts full days this year after half-day kindergarten last year. I have respectfully declined a visit from my parents over Labor Day, and DS will resume swim lessons in October. We're hunkering down and expecting the worst.
