Synchronize multiRunnable

I have 3 Runnable tasks

    PeriodRunnable runnableJob1 = new PeriodRunnable(driver, bolgaria);
    PeriodRunnable runnableJob2 = new PeriodRunnable(driver, egipet);
    PeriodRunnable runnableJob3 = new PeriodRunnable(driver, turc);

    runnableJob1.run();
    runnableJob2.run();
    runnableJob3.run();

I set 'synchronized' for my object

public class PeriodRunnable implements Runnable{
    private final PeriodCountdown counterdown;

    public PeriodRunnable(WebDriver driver, PeriodTour periodTour) {
        this.driver = driver;
        this.periodTour = periodTour;
        counterdown = new PeriodCountdown(driver, periodTour);
    }
    public void run() {
        synchronized (counterdown){
            counterdown.runCounter();
        }
    }
}

but my runnableJobs's starting work all together. What i'm doing wrong, tell me please?