Advice for WBTB

I've tried a couple of techniques before, mostly when falling asleep for the first time, but I only just started using WBTB. I set my alarm for 6:45 am, but I woke up earlier than that today. I turned off the alarm, but could not go back to sleep.

I am thinking about setting my alarm for earlier, because the sun was already out by the time I woke up.

Any advice?

BTW I usually go to bed around 12:15 am