Skip led matrix filling loop

Projects Programming
1

Hi!
I have trying to skip 8x8 led matrix filling loop by button press using mills.
Have searched different options ("NoDelay.h" library, "blink" without delay) but have not success.
So far here is the code snippet:

unsigned long previousMillis = 0;
const long interval = 234; 


void fillLedMatrix(){

  //  Start filling from bottom left
  for(int a = 0; a < matrixCount; a++){
    for(int r = 0; r < 8; r++){
      for(int c = 0; c < 8; c++){
        lc.setLed(a, c, r, HIGH);
        unsigned long currentMillis = millis();
        if (currentMillis - previousMillis >= interval) {
          previousMillis = currentMillis;
          if(digitalRead(BUTTON1) == LOW) {
            drawWordNext();
          }
        }
      }
    }
  }
}

Led matrix displayed as fully filled

2

Please provide full code.

Why do you want a timing when it comes to button presses?