Kind of a mystery. There are some semiautos whose serial numbers start with a TJ, and I found Internet references to a couple of 29s from 1991 whose serial numbers begin TJB. I think you can date your gun to the early 1990s from the fact that it is a dash-three, but I believe it will take a factory letter focused on that serial number to pick the specific date on which it went somewhere. Maybe it was a special order that was numbered in a reserved serial number range, or maybe it was a production overrun that was numbered outside of a reserved serial range to keep from confusing collectors of a limited-run model.
Either way, it looks like a nice gun and should be a great shooter. Is that a five-inch barrel? Putting together some conclusions from statements scattered in SCSW, I believe those are a little less common on the 29 and 629 Classics of the early 1990s than guns that had other barrel lengths.