I started out with a buttload of short stories about individuals in the world... after I gathered quite a bit I began my first try of teh book (which ended a week into the project since I miserably failed due to lack of skill) I then started out with an easier peice set in the future of my world and after that was done I did the actual beginning of the book.
if any of you are interested in it I got a couple of chapters here on tapas already.
Currently the most work is doing exactly what you said, getting more short stories and historian reports (the reports are tricky though since I am new to that kind of writting)
The vague Timeline is a patchwork but it will hold for the first three books... after that I will need to expand and get more stuff done. Sorry for the text wall but I am kinda excited about this project... even if it is just because I suffer delusions of grandeur.
Thank you all for the feedback! Feeling a lot more motivated now that I know people are interested in something like this.