Also: You might try going to sleep with the intention of waking up to the alarm. Think about how you're going to wake up at the time to which the alarm is set, and really know that you will get up on time for your WBTB. Do this well enough, and you might just find yourself waking up without an alarm at all. (This is a prospective memory exercise from the MILD toolbox, if you're curious).

Another thought; You might consider tossing out the alarm altogether. We all wake up fairly frequently throughout the night, even if we don't remember doing so. What you might do is learn to simply get up during a wake-up that might occur around the time you set your alarm. Then you can do your WBTB without any concern for an alarm, and without the other problem alarms can cause: they wake you up too much.