When I initially realized I was trans (17), I held off on any kind of medical transitioning because I had absolutely no financial resources and wasn't sure if my family would be supportive.
When I first started to really consider transitioning (21), I was just in a weird situation - just finished college, living with my girlfriend, but moving to grad school in a few months, on my mom's health insurance that I didn't think would cover anything, and still very much in the closet. And I still wasn't convinced that T was the right thing for me. I knew I wanted top surgery, but at the time, I hadn't connected that a lot of my dysphoria was socially driven and that T would help masculinize me enough that that would no longer be an issue.
When I finally started T (25), I had run out of reasons not to. I had come out to my family and friends and everyone was supportive. I had a good job with benefits that would enable me to pay for it. I had also done more research in that time, so it no longer seemed as intimidating as it once did.