Hey Aququarius..
recently (less than a year ago) I took a course that taught you how to teach english as a foreign language. It was a month long intensive course, 8 hours per day, plus extra for lesson planning. I listened to Personal Genius every night before I went to sleep. I would wake up early (6 am) go to the class, stay their until 5 or 6, come home (actually a hotel in thailand) and spend 1 or 2 hours preparing my "practice lessons" for the next days class. I would take a couple hour break to watch a dvd, then listen to Personal Genius, and fall asleep.
I got such good results, (instructors saying how well I did, etc, co-students saying how well they expected me to do, etc) that I think listening before sleep is best. Especially after learning something that day, take a break, and and then paralimanalize it into your brain, and let your brain work everything out while you sleep.
Jeepers creepers, this post was way longer than I planned.!
Good luck, have fun.
George