Possibility to schedule threads in Java to run at different times

I have a multithreading system that is the same as the post link - Java Thread Synchronization (synchronize collections) in Java that allows you to schedule threads to run at different times.

In this way, the agendarTarefa class receives the hour and minute of the Relogio class to create a new task Thread and threadRelogio to execute threads .

Class Relogio that contains hour and minute:

public class Relogio {

    private int horas;
    private int minutos;

    public Relogio() {
        this.horas = 0;
        this.minutos = 0;
    }

    public Relogio(int hora, int minuto) {
        this.horas = hora;
        this.minutos = minuto;
    } 
}

Class Tarefa that receives the hour and minute of a clock and creates a schedule:

public class AgendarTarefa {

    private Relogio relogio;
    private boolean estado;


    public AgendarTarefa(Relogio relogioAgenda) {
        this.relogio = relogioAgenda;
    }
}

Class ThreadRelogio to execute threads until done:

public class ThreadRelogio extends Thread {

    private final Object mutex = new Object();

    private boolean parou = false;
    private int tempo = 0;

    @Override
    public void run() {
        try {
            while (!parou) {
                Thread.sleep(1000);
                synchronized (mutex) {
                    tempo++;
                    mutex.notifyAll();
                }
            }
        } catch (InterruptedException e) {
            // Ignora.
        }
    }
}

My doubt is when threadAviao1 is created to execute after a while the program should execute the other threadAviao2 knowing that threadAviao1 has not yet finished, for this to happen it is necessary to develop a method to advance clock or is there another solution?

I have an example of a configuration of 3 airplanes to test the threads :

--- Avião ---  
Nº de Voo              : 1   
Origem                 : VENEZA  
Hora de Chegada ao IM  : 10:20  

--- Avião --- 
Nº de Voo              : 2  
Origem                 : DUBAI  
Hora de Chegada ao IM  : 10:30  

--- Avião ---  
Nº de Voo              : 3  
Origem                 : BRAZIL  
Hora de Chegada ao IM  : 10:40

So I realized every 10 seconds this method is executed executarEtapa(Aeroporto aeroporto, Aviao aviao) Source Code

public void executarEtapa(Aeroporto aeroporto, Aviao aviao) {
         //contador
         int contador = 0;
        //por enquanto a cada aviao executar uma 
        //etapa sai de executa a etapa de outro aviao
        while (contador != 1) {
            aeroporto.AviaoChegou(aviao);
            //aguardar um tempo
            aeroporto.getRelogio().esperar();
            //aviao partiu
            aeroporto.AviaoPartiu(aviao);
            //incrementa contador
            contador++;
        }
    }

Class ThreadAviao to perform airplane steps:

public class ThreadAviao extends Thread {

        private final Aviao aviao;
        private final Aeroporto aeroporto;

        public ThreadAviao(Aeroporto aeroporto, Aviao aviao) {
            this.aviao = aviao;
            this.aeroporto = aeroporto;
        }

        @Override
        public void run() {
            try {
                synchronized (mutex) {
                    while (!comecou) {
                        mutex.wait();
                    }
                List<Aviao> lista = new ArrayList<>();
                //adiciona o aviao a lista
                lista.add(aviao);
                //ordena os avioes
                Collections.sort(lista);
                //escolhe um aviao 
                for (Aviao novoAviao: lista) {
                    //inicia a etapa
                    etapaAviao.executarEtapa(aeroporto, novoAviao);
                }
               }
            } catch (InterruptedException e) {
                // Não faz nada.
            }
        }
    }

Any suggestions?