So I was reading this wiki article on Sophie Wilson, formerly Roger Wilson, who wrote the ARM instruction set for computers and seems to have been a pioneer in computer design. But I'm not sure if she represents women in the early computer industry, as she was apparently a man for most of her career. If you were writing about the history of computers, would you write it as Sophie or Roger Wilson?
Or how about Chelsea Manning, who did historically notable things while Bradley Manning? Would you use Chelsea or Bradley when writing about wikileaks?
Most trans people prefer that their current identification be used regardless of the point in their life under discussion. Personally I'm in the minority on this and have no problem talking about the boy I used to be, but that's not common.
Generally speaking, use the name and pronoun the person prefers regardless of when in their life you are talking about. If they prefer otherwise they'll let you know, but unless they've given you specific permission to do so it's extremely rude to use incorrect pronouns or refer to them with a name they abandoned.
It's a bit like a woman who divorces an abusive husband and subsequently stops using his name. It would be weird, rude, tactless and cruel to refer to her as "Mrs. Exhusbandsname," even if you're talking about something she did years ago while still married to him.
If commenting on Sophie's place in the history of computer design, it may be worth discussing how being mistaken for a man for much of her life, and the process of correcting this mistake, impacted her her career. She was a woman before she transitioned too, even if nobody else knew it.