Check if time is between two time inputs.

BulldogLowell:
this:

DailyTimer::update();

needs to be in loop() as in the example...

your blocking code is a liability...

But if the "Partymode" button is pressed I want to ignore the time settings, and just do an flashing of leds regardless of time.

As long as "Partymode" button is not pressed it should work, as DailTimer::update(); is in "dailytimetimer"

void dailylibtimer() {
  static unsigned long lastTime = 0;
  DailyTimer::update();
  if(millis() - lastTime >= 1000)
  {
    char timeBuffer[32] = "";
    sprintf(timeBuffer, "Time:%2d:%02d:%02d\tDate:%02d/%02d/%4d", hour(), minute(), second(), month(), day(), year());
    Serial.println(timeBuffer);
    lastTime = millis();
  }
}

void loop()
{
  ArduinoOTA.handle();
  Blynk.run();
  timer.run();
  if (partymodeButton >= 3) {
    partyMode();
  }
  else {
  dailylibtimer();
}
}