SP is an in between stage. You aren't fully dreaming. Other people would be better at giving tips since I have never succeeded at WILD's but I've had a few spontaneous WILD's that just happened. I have read many posts on it though. I would say, try not to focus so much on your body but more on imagery.
And I've had the small jolts too. And my psychology professor told us about it in class that it's something to do with your the balance center of your brain.