I have used the distance from Earth to the Sun (1 Astronomical Unit) as the basis for calculation.
It takes light 8.3 minutes to travel 1 Astronomical unit. ( Approximate distance Earth to Sun 93 million miles; approximate speed of light 186 000 miles per second) = 500 seconds
So, the time for the other planets is
Mercury (0.4 AU) 3.32 minutes
Venus (0.7AU) 5.81 minutes
Earth (1 AU) 8.3 minutes
Mars (1.5 AU)12.45 minutes
Jupiter (5 AU)41.5 minutes
Saturn (10AU) 83 minutes
Uranus (19 AU) 157.7 minutes
Neptune (30 AU) 249 minutes
Pluto (39 AU) 323.7 minutes
http://www.enchantedlearning.com/subjects/astronomy/planets/
Better check my arithmetic though.
The distances in astronomical units were obtained from
