They got her early. She had a few solid credits to her name when she did Iron Man 2, but the smart MCU move at that point was to recruit young-ish talent and get them signed on for multi-movie contracts relatively cheap. Hopefully what we all get out of that sort of arrangement is that talented actors make enough MCU money to go off and do whatever out-there artsy stuff that creatively appeals to them and fosters their talents, rather than having to plug away in garbage movies just to pay the bills.

My theory is that Jupiter Ascending was supposed to be a trilogy, but the studio would only approve one movie with a wait-and-see approach to the second and third installments, and the Wachowskis just said “Fuck it,” and crammed 6+ hours of plot and world building into a two-hour movie.