2018? That's 6 years from now! Anything could happen between now and then. Look back 6 years ... could you imagine then you'd be where you are today? I certainly couldn't.
Celebrate now! Go for a tour now! You don't have to do anything long or extensive at this point. Just get out there and enjoy for a week or two or three. Then do it again next year, and the following year.
All the while, build up your touring experience and collection of touring gear.
Then, if you still want to do the big trip in 2018, you'll be prepared.