Taking into account that the planet Mars orbits our Sun in about 687 days, while the Earth does the same in about 365 days, it comes down to simple math:365 * 12 / 687 = 6,38 years.
Well you'd still be eight.
Depends on what you use as your time reference.
If you used the Earth as your reference point for a year, and you went to Mars, you would still be eight.
Using Mars...