Performing a specific task on a specific date and time

I'm trying to develop a small system that sends an email every Tuesday at 08:00 in the morning.

But I'm a bit confused, I can already send the email and check if it's Tuesday, but I do not know if it's correct.

The system keeps running, but since I'm still not checking to see if it's 08:00 in the morning, it should not send multiple emails without stopping, since the only condition for sending emails is to be Tuesday?

Here is the code:

public void gerarAviso() {
    Timer timer = null;
    if (timer == null) {
        timer = new Timer();
        Calendar data = Calendar.getInstance();
        TimerTask tarefa = new TimerTask() {
            @Override
            public void run() {
                System.err.println("DATA: " + data);
                if (data.get(Calendar.DAY_OF_WEEK) == Calendar.TUESDAY){
                    System.out.println("É terça feira");
                    EnviaEmail e = new EnviaEmail();
                    e.enviaEmail("[email protected]");
                }else {
                        System.out.println("Não é terça feira!");
                }    
            }
        };
        timer.schedule(tarefa, data.getTime());
    }
}