Felix,
My suggestion (and just one of no doubt many) would be that the first time you read it, perhaps you’ll wish to read it by year. So read the bottom row (1939) of frames by page to the end. Then the same for 1959, 1979, and ending with 1999. Then once you have some idea of what to expect, experiment with other sequencings. (I’m hesitant to say that, since every reader is different, but it’s the way I now wish I had first read it.)
Again, this isn’t so much a great story as, (in Mr. Moore’s words): “ There’s something that you couldn’t do in any medium other than comics.”