I recently found an interesting website! http://sleepyti.me/
You can put in the time you need to wake up and it will tell you the ideal time to go to bed. I tried it with a 6:45 AM wake-up time:
You can also find your ideal wake time, based on when you go to sleep (does anyone else think this is great for kids?!?!?)
I put in 8:30 PM:
This goes a long way to explaining why my 4 year old gets in bed with us between 2-3 almost every night!
Check it out - it's completely free! http://sleepyti.me/ I hope you enjoy :)