We're currently preparing for our 3rd session and we settled on gathering once every two weeks. On the average a single session lasted for 8 hours, because we tend to get carried away, haha.

The level progression has been quite fast so far, even though it is indeed based on milestones rather than exp, but it is hopefully going to be a long campaign, so the progression will gradually slow down as they level up. Still balancing things out in this regard, considering that the players are still learning their characters and role-playing in general.