My general rule for any car (assuming they are fairly standard non-specialist) is change oil/filter & quick inspection at 6000 Miles, full service (oil + all filters, plugs etc) at the next 6000 miles.
Basically the car gets 'looked at' twice a year and oil gets changed twice a year.
I've a 99 Almera and although I don't have the manual with me right now, I think that both figures (15k, 9k) are correct! I've seen the service schedule for my model in Autodata and IIRC it's about every 10k miles for the first 70k or so, then it becomes more frequent. I suppose the older it gets the more care it requires.