I dont have ringing before sp, I have it 24/7. But oddly I know I'm going to have an sp episode if I'm lucid dreaming at night, because im in a scene for a couple seconds to a minute, then I freeze to the image of something absolutely terrifying. It's funny because usually self help blogs tell you that with practice you can go from SP to lucid dreaming but I'm the other way around!!
All I can say is, and please take this with a grain of salt and don't repeat, but apparently the only effective way to prevent SP is to drink enough alcohol to be tipsy, and no more, the go to sleep before it wears off. I did this, and my tolerance went up within a week.
So if anyone tells you that bit of advice, it does work, but it's a slippery slope as always.
I hope you find some reliable, safe help for your SP.