I understand the WBTB method well: waking up early, staying up doing affirmations or reading about LD’s, then going back to bed. BUT!!! What can you use to bring you from, or jolt you out of sleep, without waking others who live with you?? For the next week, I’ll be doing WBTB and doing a log of my results to post here, but i just need to know how to wake up without waking others with a loud alarm or such.
I was worried about my alarm waking others, but once trying it out, I’ve discovered it doesn’t at all. not even my baby sister who has her bedroom next to mine (with my alarm right up against the wall that seperates the two rooms).
You could try repeating your self ‘I will wake up at (X time)’ in yuor head until you fall asleep. Lots fo people have confirmed that as working (getting it right within around a half hour of the time you chose)
When I had a DJ, I woke up every 1.5 or 2 hours - without any alarms or anything, just knowing that the notepad is still under the bed. 
But as soon as I was prohibited to write anything at night, this happy time was over. 
I was not able to think out any non-material reason to make me wake earlier than 4 a.m. (I have to get up at 5 a.m.). But I do wake at four, and it never happened, that I was asleep during the alarm (it wouldn’t wake me up if I were, because it is in another room behind two closed doors).
So, maybe, you’ll only have to set the alarm clock to WBTB time several times - and then this time will be fixed as a standard time of waking… Naturally, if you are going to do WBTB not every morning, but from time to time, you’ll have to think out something more intricate. 
By the way, a plateful of soup, a mug of tea or several bunches of grapes in the evening make a good alarm clock. 