Make prints and figure out the times, then pass your meter, with all darklights out, under middle gray of the projected negative, and white and black. then make notes. You will soon find the speed of your paper.
Once you have got enough data that way you can use the meter properly. It may be possible to use the Delta black/white readings to indicate grade.
It might be designed to have a ground glass appearing filter over the probe as a sort of averaging device.
I agree with Tony, but the fun is in the journey.