Have you considered simply going to DL's website and looking at the schedule there? When you punch in a route it will give you the flights from quickest to slowest within the time period you specified.
If you don't mind getting up early, you can be in LAS by 10:25 by this route:
DL 401 dep EWR 0600 arr CVG 0755 727
DL 724 dep CVG 0910 arr LAS 1025 757