Does anybody know how to determine from the VIN, exactly when a machine was made, like is there month and year in the digits?

There is a letter in the VIN to indicate the year. If I recall correctly, H is for 2017. You can work forward or backward from there.

This is how my Z is.  Not sure if it applies to C and U models.

My Z-800 Trail VIN plate on the frame by the right front wheel has the MFG date stamped right on it, independent of the VIN.