The earliest known references to celebrations for wedding anniversaries which have symbols associated within them we have found to date are to the Silver Wedding (25 years of marriage) and Golden Wedding (50th Wedding Anniversary).
Originating in the middle of Europe (Germany/Austrian Region) they involved the husband giving his wife a silver garland when they had been married for 25 years and a Gold garland when they had been married for 50 years.
One of the noteworthy things from the above is that the celebrations were termed the Silver Wedding and Golden Wedding with no reference to anniversary hence when celebrating any wedding anniversary that has a symbol associated with, it is appropriate to just call it by the material then wedding e.g. Silver Wedding for the 25th or Paper Wedding for the 1st Anniversary.
Thus, when people refer to the Golden Wedding Anniversary they are technically talking about a subsequent year after the event e.g. the anniversary of the Golden Wedding!