Just ride as much as you can comfortably do without overdoing it and getting injured. Your butt, back and neck are more important to train than your legs. The main progress you need to make is not physical. Learn to ride safely in a wide variety of situations. Learn about bike fit, cyclotouring gear, and how to manage on the road. Read a bunch of journals over at crazyguyonabike.com to see how others have done it. Learn bike maintenance and repair. Assemble your gear. Plan a safe route.