If I complete the 7th mission stamp today but open the box after Suicune enters the game, do I get Entei or Suicune?

Title. Today is my 7th day and in my country Suicune doesn't arrive until 22hrs. I don't want to stay all day without completing missions, but don't want another Entei, I want Suicune starting today. So, if I complete a mission today and get the 7th stamp but don't open the box initiating the catching phase and wait until Suicune is released, do I get an Entei or a Suicune?