no it doesn't go by time afaik. just mileage countdown. since you paid for the service i would think you would still get an annual even if under miles. they should also reset the counter after the service is done. back in the states I had a great dealer that did the yearly and didn't reset so i could get in an extra service during the year. i also changed the oil myself in between track days anyways. good luck! are you going to the bmw school at the ring this Aug?
"It gave you amazing satisfaction, but anyone who says he loved it is either a liar or he wasn't going fast enough." - Jackie Stewart on racing at the Nurburgring