Well, not time travel as we think of it, of course. For Christ it’s just a matter of stepping into the timeline like walking through a door from one room into another. He doesn’t see time as a solid object the way we do but more as an avenue to visit humanity, as I see it. His Incarnation in time–now that’s the real miracle of time and space. Makes my poor head hurt trying to wrap my mind around it.
It works the other way too. The Eucharist we offer at every Mass is an eternal offering offered in time. We re-present the one sacrifice of Christ to God in eternity. So, Jesus appearing at any point in history would not be impossible. In that case, the only questions being did he and/or would he do that?