Based on an exp rate of 20k/hour (gained roughly from your screens, the pal gained 13k in 40 minutes ~20k an hour), and totaling the amount of exp needed from 67 - 80 (~18,000,000), your Paladin will hit 80 in 900 hours (37.5 days) of straight grinding.
Assuming you grind 8 hours a day, 5...