If the BMW is like other German brands the car can either be on a fixed service schedule or a variable service schedule. Then there's also a long-life service.
It will mainly depend on what type of mileage you are doing over a specified period of time. My diesel will only go for about 8k before the service light tells me to service, but I'm doing about 750 miles a week in her, motorway driving.
My mate has a diesel too but works local to where he lives and he gets a lot more mileage for a service.
It all comes down to the way the car is used. The service indicators are conservative anyway, so they won't let a car go without.
There are those die-hards who will say 5-8k max, but as engines improve I think this becomes less and less relevant