I recently received an e-mail from Anne in response to a question about serialization of regular Sebenzas. She said that the first 200 Sebenzas (large and small, 400 total) were serialized/engraved when CRK switched over to the "regular" Sebenzas circa the second half of 1996. The serialization (which was also done on the first 200 production Mnandis) simply demarks a new model and adds some collector interest.
The serialized run of large Sebenzas was begun around July, 1996, and the small Sebenzas followed a bit later, around November, 1996. According to Anne, they are pretty sure that all of these serialized Sebenzas were ground by Chris himself (though the outside blade profile was CNC'd). Anne stated that in fact Chris did all of the production Sebenza blade grinding until handing off the task to others in CRK sometime in 1997.
This period in the latter half of 1996 also marked two other changes to the Sebenza: the switchover to BG-42 from ATS-34, and the change in blade finish from polished hollow grind/satin flats to stonewash finish.
One final variation is the location of the serial number! Most likely the serial number is located next to the CR logo near the blade stop pin, but in early runs of the (small?) serialized Sebenza, the CR logo was engraved too close to the stop pin to allow room for the number, so the serial number was engraved near the tooling hole on the bottom right.
It is likely that there are a number of variations of serial number location, blade steel, and blade finish among these first run serialized Sebenzas!