Good question, I need to think more about it, but I believe the best time is now. I can’t imagine living in a world without corticosteroids, etc.
Discussion
It's kind of my conclusion, too. We are living in an exceptional time where "The matrix" feels close enough. What if humanity survived millions of years and to keep things interesting and engaging for our monkey brains, machines simulate this very moment in world history for us but we don't actually have physical bodies and we could pick other times but it's just the most exciting.