A good leader must have an excellent time management skill. How do you ensure that your tasks are completed on time?

Thanks 

Just you need to put a time sheet for each task, then check on it your task progres, at that time you will aware where you are and when your task be done 

thanks for the invitation Prepare a schedule for all tasks by day and date and follow up each task during its execution and by the end of the time schedule, the tasks will be completed

Well, there are number of factors and most important of all those is that, before starting execution, one must plan efficient Monitoring & Control Mechanism to keep an eye on tasks all the time and control the situation where things start getting behind timelines.