There aren't many things I can share my experience with on this site, but this is one of them. I'm in the same spot, everything is essentially ready and as I get closer to leaving I can feel a bit of that fear in the back of my head.
The positive thing I've noticed is that to me, it's the same fear I've had many times before when I was about to do something "big" for me for the first time... Jumping off a zipline or rappelling or in the lake, coming out to people the first time, meeting up with someone new, doing new drugs, etc. I've always pulled through in the end and usually ended up enjoying myself and learning new skills.
I can't say this is the same, but it seems familiar to me. Your mileage may vary, and I always suggest that people listen to what their brain is trying to tell them, but that's how I interpret mine so far. I'm hoping I run into someone who would want to head out with me, which I think would help (I have run into folks, but when they could tell I was getting ready to leave and talked with me, it threw me off and my words left me, lol). If not, in this situation, I'll end up ignoring it and pulling through like always.
Good luck!