In the configuration of Xpert-Timer you can set the option to see all due reminders when starting up Xpert-Timer.
All due reminders will be displayed in a dialog so you can immediately handle them.
Use this dialog to start your tasks immediately, change the status or set them to "Done". This dialogue can help you a lot, keeping your tasks sorted.
Additionally you'll see the desktop reminders on your screen. You can as well start a task or handle the reminder from there: