You are experiencing Schedule Change Saturday. It could keep happening up to the weekend prior to the trip, but will most likely stop with 6 weeks to go.

it’s annoying and happens way too often from certain airports. JFK and BOS to CLT are regional jets, which I feel have schedule changes more often. Your new ATL flights should be better, since they are mainline jets.

While annoying, there can be a silver lining. Delta has very lenient policies for schedule changes. If there was a flight you preferred, but it was a lot more expensive, going through a schedule change opens up the possibility to move to that flight with no additional cost.