I have a 2012 petrol.
Service is
From first registration 20,000 miles or 2 years whichever comes first. Then every 20k or 2 years from date if service.
However, if the car does less than 12k in 12 months from first registration then interim service, oil and filter change. And then at 2 years full service.
Then the 12 month rule then applies.
So in your case an interim will be required after 12 months from first registration as under 12k miles if same service requirements for your 2017 crdi.
Also, hy only allow a + of 1 month or, i think 500 miles from anniversary date to keep warranty intact.
The service hand book should give full details.
If buying from hy dealer it would be interesting what the sales person says........ but then question their response and see if it changes.
Hope car meets your expectationat the right price