Inspection due after KM or time?

Hello, I have been driving a C-Elysee for less than a year with the 1.6 liter petrol. The car serves as a supplement to me and is therefore not driven for some time, if it is then driven it gets at least 100 to 700km on it. So within 11 months good 5000km came about, whereby I did not get the car out in the winter about 5 months – all in all a beautiful life for such a vehicle, I mean. 2 weeks ago I got the car this year to the erss I then thought to myself: “Well, in May the car will be one year old, which is expected from the average driving performance, so that it will get its customer service for its birthday”. Is that correct? Today I used the car again, and it now shows 900km to customer service when the ignition is switched on, while d he ride lights up a wrench, which should probably animate to make an appointment. I find this display a bit confusing – you drive e.g. 100km, turn off the vehicle 2 weeks, and has suddenly “lost” again 500km to the next customer service. How is that with your vehicles, and: Do I interpret the whole right thing? MFG Sven