Max, should be a good plan if you have the discipline to start slowly, increase your mileage incrementally, and not push through pain during an endorphine high.
Not enough has been written on this page about the importance of your bike fit. No amount of pre-training will prevent the potential injuries due to a bad fit, injuries that can end your trip early. Small mal-adjustments are greatly magnified by the thousands of repetitions of riding.
When you get your bike, get a good neutral fit at a bike shop. This is far from the optimal venue to obtain this sophisticated procedure but it may be all you need for many miles or more (the alternative is a specialized sports med pro, often a PT, who does nothing but bike fitting/training. He analyses your stroke, bio-mechanical traits, and your bike. Riders with hard-to-solve- injuries and other riding obsessives often consult with them).
Get pedals with float (side to side free rotation) to avoid problems from a locked-in foot position.
Learn what you can about making fit adjustments just in case you end up out in the boonies with persistent and increasing knee or back pain. Remember that adjustment in saddle height, for-aft position, rotation, stem height, handlebar rotation, etc should be in millimeters and fractions of a degree of rotation. SMALL. Then give your body time to show improvement.
I hope you do well out there. Should be one of your life benchmarks.