"Von" indicates the ancestral possessions of the noble. Usually it was a village or villages awared to his or her ancestors by the king.

For example, Sophie Chotek von Chotkow und Wognin is from an old noble family with an old seat in Chotkov, later moved to Vojnín.

That's where it originated, but later "von" was put before the original surname when the person was awarded the noble status.

"Von" can also indicate the place of origin and desn't have to be an indicator of noble origin. The dutch "van" means the same thing, but it almost never indicates noble origin.

I thought von was an Uradlichen nobiliary particle, in essence meaning that it dates back further than we have record of making it impossible to trace exactly when the practice started?

I know for a fact that old noble families in northern germany and those of prussian descent abbreviate the von to v. in writing to distinguish their names from the non-noble von and the younger noble families.