5A.M. would likely be at the end of the first sleep cycle.

I am quoting the DEILD Tutorial from the DV WIKI

Set it to go off after between 3-6 hours of sleep. You'll have to experiment to find the best time for you. If you want, you can also set it to go off every half hour after that, to give you a greater chance of waking from a dream.
Visit the tutorial and read over it. Get an idea of what to expect and think about your normal sleep schedule and how the technique fits in.