Depending on your recording settings, and the amount of motion that the cameras are seeing, it is very likely that any recordings for 2017 have already been overwritten by now.
On an 8ch system with a 1TB hard drive recording 24 hours per day every day, typically you get between 7-10 days.
This time is extended by having fewer cameras, less motion, or changing your recording settings.
The basic recording setting only records 1 frame every 5 seconds when there is no motion, and then 30 frames per 1 second when there is motion. It can extend the recording time by months depending on how much motion there is.