#define INTERVAL_MESSAGE1 5000
#define INTERVAL_MESSAGE2 7000
#define INTERVAL_MESSAGE3 11000
#define INTERVAL_MESSAGE4 13000

unsigned long time_1 = 0;
unsigned long time_2 = 0;
unsigned long time_3 = 0;
unsigned long time_4 = 0;

void print_time(unsigned long time_millis);

void setup() {
    Serial.begin(115200);
}

void loop() {
    if(millis() > time_1 + INTERVAL_MESSAGE1){
        time_1 = millis();
        print_time(time_1);
        Serial.println("I'm message number one!");
    }

    if(millis() > time_2 + INTERVAL_MESSAGE2){
        time_2 = millis();
        print_time(time_2);
        Serial.println("Hello, I'm the second message.");
    }

    if(millis() > time_3 + INTERVAL_MESSAGE3){
        time_3 = millis();
        print_time(time_3);
        Serial.println("My name is Message the third.");
    }

    if(millis() > time_4 + INTERVAL_MESSAGE4){
        time_4 = millis();
        print_time(time_4);
        Serial.println("Message four is in the house!");
    }
}

void print_time(unsigned long time_millis){
    Serial.print("Time: ");
    Serial.print(time_millis/1000);
    Serial.print("s - ");
}