A few months back, I scheduled a session with my therapist to discuss exactly this question. I had a lot of fears of the "what if" variety and they were paralysing me. Because of a winter storm and the length of the drive to see her, I stayed overnight in the city, which gave me an evening and a morning to kill. I decided to try some RLE while I was there, since no one would know me except the support group friends I hung out with that evening. I had a ball, enjoying every minute of the RLE and feeling empowered. I went to a bar with my trans friends, had breakfast at a coffee shop, and went window shopping. I even had a laugh about my identity when I bought something in a co-op store that I am a member of; the cashier keyed in my member number, looked at the screen and asked, "<deadname>??" I said, yes, I guess that would still be the name on my account; I guess I'll have to change that. It was all good.
My therapist session was inconclusive. She told me that, if I wanted to address the fears, I would need to schedule more appointments and do a bunch of work.
When I got home again, I realized several things:
1. The empowered feeling didn't go away when I got home.
2. I was already planning to go full-time in three weeks.
3. I was not going to change that plan over a few "what ifs".
4. Additional therapy sessions to address the fears were unnecessary, because I was going to go ahead no matter what.
As a result, the paralysing fear faded to nothing more than a bunch of squirrels chattering in the back of my mind. It was the self-confidence of spending a day out in public as myself that did it. I have been in to the city before as myself when I go to the support group, but I don't usually interact with others in those trips. This time, I was by myself and interacting with strangers and enjoying it.
The squirrels still chatter. They have their function: if there is real danger, I am counting on them to spot it and alert me. But now, my attitude is that if people have a problem with my existence, <not allowed> 'em.