Finding a Kerr Black Holes
1) Nearly all black holes are Kerr black holes.

2) There are roughly 100 million black holes estimated in our galaxy.

3) There is a confirmed black hole about 7800 light years away.

4) There is a potential black hole about 1500 light years away.

5) It is very likely that there are black holes even closer than that, but they are difficult to detect.

Some of your assumptions are wrong, but for now the closest known potential black hole is still a pretty good distance away. Traveling that far with our current technology is impossible, and overcoming that hurdle is not trivial. Regardless, using a Kerr black hole for time travel may not be feasible anyway.