Two things can happen to the fluid. It can smell slightly burned. Or it can be dirty. I assume it's dirty and doesn't smell.

Just change it now. I don't have a manual in front of me but I assume there is a filter to change in the transmission pan. I'd change it if there is.

The big thing that happens is that not changing the fluid puts a little more wear on the parts. I just gave my brother a 1992 Accord with 172k on it. I got it from a friend at 150k. I never changed the fluid and I don't think he did either. It shifts fine.