Assume you have all the luxuries of a modern life in your Tardis (toilet, hot showers, TV, books, game console, …) which doubles as a mini self-sufficient apartment with it’s own energy stores and generation.
Where in history would you go if comfort wasn’t an issue?
I’d go back and see if I can find Jesus. See what he looked like, what he actually said at his sermons, and what happened after the crucifixion.
I mean he disappears for a few days after and seems good afterwards before vanishing forever, so chances are you were there and you intervened