When did they first notch the rivet?

I was just this minute reading up on the 'naff on this ... it says:

Authentic rivets (the back of the studs) are very slightly convex. Since 2005 (inconsistently in spring/summer bags; consistently since fall/winter), the rivets have a notch on either side. Before 2005, the rivets were a simple circle.
 
I was reading the how to tell if a bag is fake thread and it said that after 2002 the bags started using notched rivets. However, my 2004 bag has solid rivets. So when exactly did the notched rivets start? TIA!
 
Feifei, most of pre-spring 2005 bags have solid rivets, whereas spring/summer 2005 bags seem to have already transitioned to notched rivets. However, as the other gals noted, sometimes bags from those two batches are inconsistent regarding the presence/absence of notches. You can have a look in the Reference section for some good sections of rivets from different seasons: http://forum.purseblog.com/balencia...-pics-hw-need-year-style-close-up-149618.html