Answer:
The dwarf planet Makemake is a "Kuiper Belt Object", which orbits far out from Neptune. The travel time will depend on the speed, and so far, there is no vehicle made that can do the journey at all.
If it were critically important to do so, a crash project to launch a robotic probe to Makemake could probably be complete in about 8 years, with about 5 years travel time after launch. It would be VERY expensive, but the technologies developed would be invaluable.
I think it took about 3 million years. Ignore that persons answer!