VS 2008 Counting Down From 30 Mins?

I've done what I thought was a lot of work with DateTime and Timespan but what I am trying to do now I cannot figure out. It seems simple enough but I can't think of the code I need to make it work >.<

Currently I am using a timer to tic on 1000ms to count down a timespan. However, what I would like to do is set a timer for 30 minutes. I would like to display the minutes:seconds of the timer on a label and perform actions when the minutes and seconds are specific values, say minutes = 5 AND seconds = 0 to perform an action when the timer reaches 5 minutes exactly.

My goal is to have a 30 minute timer that performs actions at specific times, then when the timer reaches 0:00 it restarts at 30:00 This seems like such a simple task but I cannot for the life of me figure out where to start.