What I found most effective was to substantiate story points with historical data to draw the mapping between points and days. After a good period of time, e.g. 3 months, of a team working together and estimating just in points you will have enough data to draw a 95%ile of how long a 1 pointer / 2 pointer etc takes for that team. It is giving us huge gains and confidence.
So the golden question is what to do in those 3 months? How will we bill the client?
In another team I’m currently leading we’re using a 3 point estimate system (in days), and then retro-estimate quickly in a retrospective in story points. The question asked is : “Now that we’ve accomplished this story, how complex was it (using a Fibonacci sequence)?”. Not much thinking, just gut feeling. 3 months from now I will hopefully be in a position to switch completely to story points.
