Time management generally means selecting the most important things to do given limited time. And in context of aviation that means following the common maxim “aviate, navigate, communicate”. Which is occasionally called a checklist, but usually not.
Aviate means keeping the plane under control and inside the flight envelope, navigate means knowing where you are and where you are flying, and communicate if there is someone who should know, meaning mainly the air traffic control. And most checklists, except some memory items, only come after these three.
So an accident due to poor time management means the crew got preoccupied with something and basically forgot to monitor the flight path—there is plenty of those—and despite correctly executed checklists means the distraction involved a checklist, probably a non-normal one (dealing with some failure)—I am not sure how close the accidents I can remember of the top of my head come.
Eastern Air Lines flight 401 on 29th December 1972 is probably the best known accident that comes to mind. The crew executed their before landing checklist, but that revealed one issue. And the crew became so preoccupied in troubleshooting it that they failed to notice they inadvertently turned off the altitude hold.
In some sense the Dana Air flight 992 on 3rd June 2012. The crew correctly configured the aircraft for best glide in response to a dual engine failure, but then the pilots kept trying to restart the engines and neglected to prepare for the possibility of forced landing. The checklist for engine failure does mention this though, so ultimately they didn't execute it correctly.
The Distraction in cockpit category on the Aviation Safety Network seems most relevant, but not sure which of the accidents qualify. Maybe this Avianca 727 on 17th March 1988 or this Sky Executive L410 on 21st May 2002?
There is probably more, but it is relatively hard to search.