In order to be eligible for rewards, players need to have done at least one battle (participated in the Surge.)
Surges run from 11:00am CT and end the NEXT DAY at 11:00am CT. So a battle must have been done within that time frame. The rewards are sent out right after surge ends.
Example: April 1st 11:00am CT a new surge starts, so it will end the next day on April 2nd at 11:00am CT. If a player does not do one battle for this Surge, then they will not get any reward on April 2nd for the surge that just ended.