Can I resolve Evelynn and Star Spring before a dragged-in showdown starts?

Kha'Zix and hidden Evelynn are at Star Spring. I reveal Evelynn, want Star Spring to trigger first then Evelynn so I drag a unit in, trigger Kha'Zix, Star Spring Kha'Zix back, and end with Kha'Zix at +4 Might.

Must the showdown start before I can reorder Star Spring and Evelynn?