Of course the preparation for such a journey starts very early. You are concerned with the destination and about whether and how to implement this journey for a long time.
In fact I have been thinking about a travel route to Asia for a few years. At first, the idea was to travel to and through China by land. A bike ride would take too long, a ride on the motorbike is not an option for me because you're not allowed to travel in China with your own vehicle without a guide. At some point - inspired by other motorcycle travelers - the idea came up to make a round trip to the east not including China.
The concrete planning and preparation then still took almost a year. The route and time planning costs a lot of time. In the months and weeks just before the trip, I was caring a lot about visas and the preparation of the motorcycle and gear.
This time was quite hectic, so I barely had an opportunity to record the preparations. Therefore, a lot is missing here.
A word on the many websites with information on such a trip: Do not be too impressed by other people who have already done a similar trip! Such reports have often irritated me and made me wonder if I am even able to endure such an adventure. From my experience I would like to tell you: If I can make such a trip, then anyone else can do it!