I haven't played Microscope before (let alone combined with Dawn of Worlds), but I can say that you should expect this to be long. My group went through DoW at the start of our last campaign. It was really fun, and gave a lot of backstory and stuff for the world, but it took about as long as our typical D&D session (6ish hours) by itself. To be fair, we did more than the suggested 10 turns per age, but I feel like cutting it down to 10 would have made the world kind of bland. There just weren't enough points (especially in the First Age) to do everything that we wanted to do.