For me, I have no set bed-time (then again, I am in college). Even so, I still try to keep a regular schedule.
On school nights, I fall asleep by 2130 or 2200. If I am desperate, I can push it to 2230. (Or, if there's some sort of an event, e.g. an intramural sports event that I am participating in, I fudge the bedtime.)
On non-school nights, it is variable, but it is "never" (well, almost never) later than 2300.
Every day, I wake up at 625 (or within a ten-minute window of that) (Yes, even on non-school days!!)
So, getting 7.5 to 9 hours isn't bad, I think!