Driving 1,500 miles takes an average of 3 to 4 days depending on how many miles you drive per day and how often you stop for a break from driving.
I drive at most 500 miles in one day so if I were to drive 1,500 miles it would take me 3 days of driving to complete the 1,500 miles.
Driving 500 miles would take between 11 to 14 hours to complete per day so you'd drive between 11 to 14 hours per day on the road trip.
You need to pull over and sleep so don't try driving any further than 800 miles in a day unless you have a second driver who is well rested.
Then you could switch drivers and sleep while the other person drives.