Thanks for tagging,
If you bought it and never checked or changed differential oil, you should do it. As per service manual (Pajero Mini 1995 660cc), it should be good up to 90k KM for non LSD diffs, it should be similar for Jimny as both are in same class.
However, I'd recommend to change it around 50k KM mark max as our road conditions are pretty bad compared to Japan or Russia. We've lots of pot holes with water filled in them, and there's good chance there will be contamination early on.
Buy from your favorite brand's official dealer only. Fake oil can ruin it before reaching service interval.