WBTB: Waking Up Early?

[Liolar]

I've been trying WBTB recently, and know that I should get at least six hours' sleep before waking up; last night I went to bed at 2:45 a.m and set an alarm for 9:00, but I' ve woken up at 7:30; what should I do about waking up early? Should I go straight back to sleep to make up for lost time, then when up at my intended time and have my period of wakefulness? Or should I have my period of wakefulness earlier (when I woke up naturally), cancel my original alarm, and then go back to sleep?