For me, it came in multiple stages, though I'm also a couple letters on the acronym. The first time I felt something was "off" about my gender was around 4, looking in the mirror and feeling like the 'boy' I was seeing wasn't me. I realized I was trans by the time I was 12, then immediately buried it so deep I actually forgot about it. At 16, I realized I liked men as well as women, and came out to my parents at 18 (that did NOT go well). It took me 2 more years before I realized again that I was trans, and by the time I was 21 I had moved out and started living full-time as myself. Then, a few years later I realized I was polyam as well. I'm 37 now, and honestly cis-het culture just seems so alien to me anymore. Almost all my friends are either queer, disabled, or both! I just left my non-binary spouse, and I have a wonderful girlfriend now.