Hello,
I am an Arduino beginner and have tried to do it by myself. Unfortunately it does not work.
I would like my Demo LED effect to turn on after 3 minutes, but it does not turn on. Therefore I am looking for some help. Could anybody please help me and say where the error is in my sketch.

#include <Adafruit_NeoPixel.h>
#include <TimerOne.h>

#define PINR 6         

int led_ring = 60;   //  Leds (Ring)

Adafruit_NeoPixel ring = Adafruit_NeoPixel(led_ring, PINR, NEO_GRB + NEO_KHZ800);
boolean Demo = false;
int command = 0 ;     
uint32_t c;
int all_x_minut=3;   // 

void setup() 
{
  ring.begin();
  ring.show();    
  ring.setBrightness(75);
  Serial.begin(9600);
  
  Timer1.initialize(all_x_minut*60000);
  Timer1.attachInterrupt(Demostart);
}  

// ************** Programm ********************

void loop() 
{
  if (Serial.available() > 0) 
  {   
    Timer1.initialize(all_x_minut*60000);
    Demo == true;
    command = Serial.read();
     {
    } 
  }   
  
  if (Demo == true)
  {
    Demomodus();
  }  
}

// *************** Funktionen ********************

void rainbowCycle(uint8_t wait)        
{
  uint16_t i, j;
  for(j=0; j<256*1; j++) { // 5 cycles of all colors on wheel
    for(i=0; i< ring.numPixels(); i++) 
    {
      ring.setPixelColor(i, Wheel(((i * 256 / ring.numPixels()) + j) & 255));
    }
    ring.show();
    delay(wait);
  }
}

uint32_t Wheel(byte WheelPos) 
{
  WheelPos = 255 - WheelPos;
  if(WheelPos < 85) 
  {
    return ring.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  }
  if(WheelPos < 170) 
  {
    WheelPos -= 85;
    return ring.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
  WheelPos -= 170;
  return ring.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}

void Demomodus() 
{
 rainbowCycle(55);
}  

void Demostart() 
{
  Demo == true;
}

Thank you in advance and kind regards!