The earliest start seems to be Omura Sumitada in 1565 (Nagasaki), after a while his birth family, the Arima, and some of the Goto convert. By 1582, there's Otomo Sorin and there's Takayama Ukon. At least as far as the more more famous ones go — I'm sure I've missed one or two others.

So I wonder, is it better to test and push your proverbial luck as Sumitada (difficult to expand if you try to roleplay without backstabbing or overt landgrab), or fast-forward to Sorin (who is 'strong enough', as the authors say), or someone else?

Or, for better experience, is there anything like events surrounding the coming of missionaries, so that you can start as anyone and just convert the first thing when they come?