On the side note, I learned an interesting way of managing date expectations between marketing and development teams after paying a visit to one of the Hamburg-based startups. There the teams were not estimating user stories also. Instead of the development team estimating the whole product development part and giving the release date to the marketing team upfront, they have calculated how long marketing team needs on average to prepare promoting campaigns and roll them out. On average that was 5 weeks. So now, instead of giving a rough estimate upfront, development team was getting in touch with marketing team only when they were confident that they could ship the product in 5 weeks.