Hi David,
To prevent the next task from appearing in your To-Do list until the previous one is completed, you'll need to set either a Start Date or a dependency for each subtask.
If you frequently create this type of task, you can use your existing task as a template. With "New from template" option you can create a new set of tasks with the correct date intervals - the dates will automatically shift to the current ones while keeping the intervals and other task properties intact.
For more information on creating tasks from a template see this guide: Create from Template.