the excellent suggestion to try some shorter trips first is a very valid one. You will learn that you took waaaay too much stuff, or that you missed X or Y thing, and you figure out the rythmn of the road---how to eat properly, sleep properly, have X amount of food snacks with you, how to plan a days ride, how to pace yourself etc etc etc ad nauseum.

again, weekend trips can help sort out "stuff", as well as getting used to being on the road with cars and how to react etc.