This may be an unpopular opinion, but I don't think you're ready.
SI is automatic and built in. It's the reason why people rip the plastic bags off their heads. Why people flinch and make hesitation marks when they're cutting. Why they vomit the poison. That's not their brain, that's reflex. That's SI.
Fear is something else. It's an emotion. It's something you have to overcome consciously or be so disconnected from yourself that you are not feeling your emotions.
When I was at my worst, there was no fear. In fact, there was no guilt, no anything. I was almost in a trance, completely clinical about the whole thing. Now I'm glad that things worked out the way they did, but at the time I wasn't even disappointed. when I was stopped. I was just as clinical and just as ready.
Your fear might just be a stalling technique of your brain, but I tend to think it might mean something more. What exactly are you afraid of? I think the answer to that question will really help you decide if it's more preparation you need, a method you trust more, or that you're just not ready to go.
Of course, I could be full of shit. This is based on my own experience, so YMMV.