Early SP?

So I went to bed last night, and I decided to use munchohumpty's method of present tense mantras. I settled on my pillow, and found this ultra comfy spot.
I didn't feel like moving, so I didn't. All the while I was repeating 'I am in a Dream' and 'I'm doing reality checks'. Still lying there, I thought of my day and my experiences (I went tubing on a lake). I thought of the motions that I was doing while tubing (flipping, rotating, etc). These feelings started to get unusually realistic, like I was actually moving, but not moving in bed. Within 5 minutes of going to bed...

It hit me O.o

I wasn't trying to achieve SP, but I just wanted to go to sleep with that mantra in mind.
However, my body got REALLY heavy all of a sudden, colorful swirls invaded my vision, I heard a high pitch whine in my ears, my body started vibrating violently, and the motions I was picturing got uncomfortably realistic.
This SP scared the living s*** out of me, as I was not expecting SP this early, or at all!

Two Questions: How do I transition from a SP into a LD, and is it possible to do this that early?

If you're truly in sp, you should be able to jus roll out. Or you couldve just willed yourself into the pictures in your head. And if you did get sp that early then I guess it is possible right, lol. You mustve been pretty tired.